This page augments the [[FOCS Scripting Tutorial]] (which should be reviewed first) and describes in more detail the scripting language used to describe much of the content of FreeOrion. This language is sometimes referred to as the FreeOrion Content Script, or "FOCS". Scripted content includes scripted descriptions of technology, buildings, and specials. These content files are text files, but some of them include special characters and therefor when editing them a somewhat more advanced editor is necessary. For example, on Windows, the Notepad and Wordpad editors can cause trouble, but [http://notepad-plus-plus.org/ the third party NotePad++ editor] should be fine. An added benefit of using NotePad++ is that one of our contributors has made an [http://www.freeorion.org/forum/viewtopic.php?f=15&t=7161&hilit=focs+notepad&start=0 add-on to help with the FOCS syntax].

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Contents of this document have not undergone public review. --drek

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=Introduction=

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=Content Files=

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Each tech, building, and planet special will probably be encoded as XML, including mark-up tags describing the effects of the object.

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In v.3, if these are the only two classes of effects: Modify Meter and Unlock Item. An objects can have multiple effects, but no conditions beyond what is offered by the Effect Classes.

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FreeOrion content is described in content files located in the /default subdirectory of the main FreeOrion game directory (typically 'C:\Freeorion').

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=Modify Meter=

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Directory | Contents

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--------------------+--------------------------------------

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techs | Tech Categories and Technologies

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buildings | Buildings

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specials | Specials

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ship_hulls | Ship Hulls

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ship_parts | Ship Parts

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species | Species

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ship_designs | Ship Designs

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monster_designs | ShipDesigns to use as space monsters

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==Effect Name==

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The files in these directories contain descriptions of individual entries of their respective contents. buildings/ contains files with "BuildingType" descriptions (see below). specials/ contains "Special" descriptions. techs/ contains tech category and tech descriptions. When there are multiple entries in a single file, the ordering of entries in the files do not matter. Files can be organized into sub-directories as needed, for example ship_parts might contain a directory for weapon entries.

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The name of the effect, mostly for internal usage. Effects can share the same name, meaning they will not stack if the stacking flag is set. Effects that share names should have identical bonuses.)

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(programming note: "sharing a name" means that they share the same StackingID.)

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The primary building blocks used to specify the above types of FreeOrion content are ValueRefs (value references), Conditions, and EffectsGroups (which contain Effects and Conditions). Effects change the game state and thereby give buildings, techs and specials their in-game purpose. Conditions act to filter a starting set of objects to a smaller set (which might sometimes wind up being one or none). In EffectsGroups Conditions determine if (the activation condition) and on what (the scope condition) effects act. Conditions also have a few other uses, such as determining where buildings or ship parts or hulls can be produced, and where species focus settings can be used; they are also used within some of the more advanced ValueRefs. ValueRefs provide values used by the other portions of the script. Sometimes that might be a simple constant, like three, which the scripter would simply write as "3". Other times that might be a dynamic value such as the current game turn number, scripted as "CurrentTurn". In other cases that might be something much more complex, such as the number of monsters within two starlane jumps of a given system; the syntax for such value references is described farther below.

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==Scope==

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=Scripting Format=

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* Galaxy The effect operates on the meters of every planet in the galaxy

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* Empire The effect operates on the meters belonging to every planet in the empire.

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* Sector The effect operates on the meters belonging to the planets contained by the Target system and any planets in systems connected to the target system by a starlane or wormhole.

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* System The effect operates on the meters belonging to the planets contained by the Target system.

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* Planet The effect operates on a single planet.

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==Effect Affiliation==

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In FOCS, whitespace (spaces, tabs, and line endings) is only for the visual clarity of the script, and capitalization is ignored for everything outside of quotes.

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* All: The effect influences the meters of every planet, regardless of empire affiliation.

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* Exclusive: The effect only acts on planets owned by the target Empire.

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* Friends: The effect only acts the meters of on objects owned by the target Empire and allied Empires. (not required in v.3)

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* Enemies: The effect only acts the meters of objects owned by empires unfriendly with the target Empire. (every empire is considered unfriendly in v.3)

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==Meter==

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Words in quotes, eg. "NAME" are case-sensitive names of scripted content items such as techs, buildings, or specials. The names of the items are defined in their description by their line:

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* Farming

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name = "NAME"

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* Industry

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These items may be referred to in other items' descriptions by "NAME". This might typically be done when unlocking a building with a tech, or adding or checking for the presence of a special to or on an object.

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* Mining

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* Science

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* Economic

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* Health (growth of Population)

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* Construction (growth of Infra)

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* Enviroment (The results of Enviromental Preference)

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* Security (not in v.3)

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* Happiness (not in v.3)

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==Type of Modification==

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Comments may be added to files using c/c++-style comment blocks. Anything in such blocks will be ignored when parsing the content files. Anything after "/*" will be ignored until the next occurrence of "*/" (even if it occurs several lines later), and anything on a line after "//" will be ignored.

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* Additive The default.

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* Multiplicative Should be used rarely. The Modification value is multiplied with the Multiplier of the meter. (The Meter’s multiplier is then multiplied with the meter itself after all effects have executed.)

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==Value of Modification==

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In the FOCS descriptions below, the fixed portion of the FOCS specifications are in lower case or MixedCase; things written in ALLCAPS are placeholders for scripted subcontent. That type of any such piece of scripted subcontent below is specified either as a Condition, an Effect, an EffectsGroup, a string, an int (integer), or a double (a "real" number such as 2.4). In many cases, any such string, int or double can be provided either as a simple constant or as a more complicated scripted ValueRef. In any situations where a plain constant is required (but not a ValueRef), we endeavor to specify those values as string_constant, int_constant and double_constant.

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The value that is added to or multipled with the meter.

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==Stacking==

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==Specification Components==

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Does the effect stack?

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There are a number of specification components that are used by multiple different content types, and some that are particular to a specific kind of content. The more common components are described first below.

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==Focus Condition==

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===ValueRef===

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* None Effect occurs regardless of planet focus

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A ValueRef is a type of FOCS construction which gets evaluated to provide a value, and which may reference various objects and which may have conditional aspects; their structure is described in more detail below. The most common types are string (text) ValueRefs (which generally evaluate to the name of something, such as a species name "SP_HUMAN"), integer ValueRefs (which evaluate to an integer, such as 42), and double ValueRefs (which evaluate to a "double", a programming term for a "real" number, i.e., it may have a decimal point, such as 3.5). Some ValueRefs may evaluate to a kind of FO-specific value such as a PlanetEnvironment or PlanetSize; it may be helpful to think of these as a string or number for which a limited group of values are acceptable.

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* Primary Effect only occurs if the Meter being modified is set as the Primary

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* Secondary Effect only occurs if the Meter being modified is set as Primary or Secondary

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==Infra Condition==

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===Condition===

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If total infrastructure is less than this value, the effect is canceled.

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A FOCS Condition acts as a kind of filter on objects in the FO universe. Conditions start with a set of objects, and return subsets of this set according to whether the objects meet the criteria of the condition. Just what that starting set of objects is depends on where the Condition is used, and is discussed more below. There are many different types of FOCS Conditions, and their structures are also explained further below.

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==Enviromental Condition==

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===Name Specification===

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Either None, or the Enviroment in which this effect operates:

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name = "NAME"

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Param Type:

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NAME string_constant

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When displayed to a user, the name will normally be used as a key/label for which a value will be looked up in a stringtable (to enable translation); the raw FOCS name strings themselves are by convention written in ALL_CAPS_WITH_UNDERSCORES. They should generally be unique to that particular piece of content-- even if both pieces of content might be suitably translated to the same name in English, that might not be the case for other languages. As examples, the name of the first refinement of the first tier of short range weapon parts (which is currently called "Mass Driver 1" in English) is specified as

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name = "SR_WEAPON_1_1"

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* Terran

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===Description Specification===

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* Ocean

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description = "DESCRIPTION"

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* Swamp

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Param Type:

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* Toxic

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DESCRIPTION string_constant

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* Inferno

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As with the name, the description is normally used as a key/label to be looked up in a stringtable, an example (specifically, for Mass Driver 1), would be

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* Radiated

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description = "SR_WEAPON_1_1_DESC"

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* Barren

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* Turdra

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* Desert

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* Gaian

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==Description==

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===BuildCost Specification===

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Appended to the tooltip of the affected meter.

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buildcost = BUILDCOST

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Param Type:

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BUILDCOST double (ValueRef)

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=Unlock Item=

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===BuildTime Specification===

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buildtime = BUILDTIME

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Param Type:

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BUILDTIME integer (ValueRef)

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Techs, buildings, and ship parts can be unlocked. An unlocked Tech can be researched, an unlocked building or ship part can be constructed.

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===Location Specification===

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location = LOCATION

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Param Type:

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LOCATION Condition

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In general, the Location specification constrains where/when the respective content can be built, or in the case of a Focus, be used. More detail is provided below for the various particular content types that use a Location specification. For things that can be built, if the item is under construction and the Location condition ceases to evaluate to True, then progress on the construction halts until such time as the Location condition again becomes True.

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===EnqueueLocation Specification===

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EnqueueLocation = ENQUEUELOCATION

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Param Type:

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ENQUEUELOCATION Condition

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The EnqueueLocation condition sets the constraining condition under which the respective content (or a ship design using the content) may be placed on the Build Queue. If not explicitly specified, the EnqueueLocation condition will default to be the same as the Location condition. The EnqueueLocation is only evaluated at the time of placing the item on the queue; it need not remain true (and so, for example, may prohibit that the subject content is already enqueued at that location).

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===EffectsGroup Specification===

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EffectsGroup

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description = "DESCRIPTION" [optional -- may be left out]

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scope = CONDITION

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activation = CONDITION [optional -- may be left out]

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stackinggroup = "STACKINGGROUP" [optional -- may be left out]

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accountinglabel = "ACCOUNTINGLABEL" [optional -- may be left out]

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priority = PRIORITY [optional -- omission defaults to 100]

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effects = {EFFECT|[

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EFFECT

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EFFECT

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EFFECT

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]}

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Param Types:

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DESCRIPTION string_constant

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SCOPE Condition

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ACTIVATION Condition

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STACKINGGROUP string_constant

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ACCOUNTINGLABEL string_constant

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PRIORITY int_constant

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EFFECT Effect

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Describes the mechanism by which game content such as Techs, Buildings or Specials interacts with and alters the game state.

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* Consists primarily of:

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** One or more Effects

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** A "SCOPE" condition which indicates the objects in the scope of the Effect(s). The scope objects are those that are acted on by the effects in the effects group, i.e., what the targets of the effects are.

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** An "ACTIVATION" condition (assessed specifically against the Source) which indicates whether or not the Effect(s) will be executed on the objects in scope during the current turn. The default if the activation clause is left out, is to be on/active.

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For scope conditions, the entire game universe (or rather, all objects in it) are the initial set. For activation conditions, the initial set is the source object of the effects group. This allows an EffectsGroup to be activated or suppressed based on the source object only (the object to which the EffectsGroup is attached). If the source object meets the activation condition, the EffectsGroup will be active in the current turn.

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* The translated stringtable entry in "DESCRIPTION" is amended to the source objects description (at the time of this writing, only for specials and species).

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* An EffectsGroup's stacking group determines when it should affect a specific target; if that target has already been affected by another EffectsGroup with the same stacking group, all EffectsGroups after the first have no effect on the target that turn. For instance, if an EffectsGroup is in a stacking group "WONDER_FARM_BONUS", and executes on a target object, no other EffectsGroup in the "WONDER_FARM_BONUS" stacking group will affect it on that turn.

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* The presence of "ACCOUNTINGLABEL" being specified indicates this effect should be accounted for with the supplied stringtable entry. This is typically used in providing feedback to the player, accounting for this EffectsGroup among the totals of effected meters.

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* "PRIORITY" is the order of the EffectsGroup processing. Processing starts from 0, with all EffectsGroups of the same priority executing before any of a later priority. This value must be an int and is specifically NOT a ValueRef ('1 + 1' is not allowed). Information on reference priority values, and the relative priorities of the set of population effects, can be found [[EffectsGroup_Priority_Standard_Values | at our EffectsGroup Priority Standard Values page]].

* Each tech may optionally have one or more EffectsGroups associated with it.

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** Tech EffectsGroups are use as their source object the capitol planet of the empire that researches the tech.

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* All of a tech's prerequisites must be known before a Tech can be researched.

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* The note{{CN}} about Special and BuildingType name and description text also applies to Tech names, descriptions, and category names.

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* GRAPHICFILENAME should be relative to the art directory. So it should appear in the form "foo/bar.png" instead of "default/data/art/foo/bar.png".

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* Techs used in the game are stored within [https://github.com/freeorion/freeorion/blob/master/default/scripting/techs/ techs]. These files include examples of theory techs with no effects or unlocked items, as well as applications that unlock buildings or which have effects of their own.

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* The Source for all EffectsGroups in a Tech is the Empire Source (generally the Capital), as discussed in the [[#Source.2C_Target.2C_RootCandidate.2C_LocalCandidate | Source]] section.

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===Ship Hull Specification===

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Hull

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name = "NAME"

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description = "DESCRIPTION"

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speed = BATTLESPEED

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fuel = FUEL

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stealth = STEALTH

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structure = STRUCTURE

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slots = [ [optional -- may be left out]

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Slot type = SLOTTYPE position = (X, Y)

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...

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]

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(common params)

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icon = "ICONFILENAME"

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graphic = "GRAPHICFILENAME"

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Param Types:

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NAME string_constant

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DESCRIPTION string_constant

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BATTLESPEED double

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FUEL double

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STEALTH double

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STRUCTURE double

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SLOTTYPE ShipSlotType

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X, Y double, double

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ICONFILENAME string_constant

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GRAPHICFILENAME string_constant

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A specification for a ship hull.

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* Hulls must each have a unique name.

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* Each hull may optionally have one or more EffectsGroups associated with it.

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** Hull EffectsGroups are use as their source object the ship in which the hull is located.

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* ShipSlotTypes are currently: External, Internal, and Core. These can be combined within brackets and separated by a pipe ( [EXTERNAL|INTERNAL] )

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* X, Y are the coordinates to place the slot (overlaying the hull) in the ship design window.

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* The note{{CN}} about Special and BuildingType name and description text also applies to Hull names and descriptions.

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* ICONFILENAME and GRAPHICFILENAME should be relative to the art directory. So it should appear in the form "foo/bar.png" instead of "default/data/art/foo/bar.png".

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* Hulls used in the game are stored in [https://github.com/freeorion/freeorion/blob/master/default/scripting/ship_hulls ship_hulls].

* Each part may optionally have one or more EffectsGroups associated with it.

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** Part EffectsGroups are use as their source object the ship in which the part is located.

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* The note{{CN}} about Special and BuildingType name and description text also applies to Part names and descriptions.

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* ICONFILENAME should be relative to the art directory. So it should appear in the form "foo/bar.png" instead of "default/data/art/foo/bar.png".

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* Parts used in the game are stored in [https://github.com/freeorion/freeorion/blob/master/default/scripting/ship_parts/ ship_parts]].

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====Ship Part Class, Stats and PartMeters ====

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Each class of ship parts defines a primary stat and may also define a secondary stat. Some have associated ship part meters (One meter value per ship object and ship part meter type). Possible ship part meter types are: Capacity, MaxCapacity, SecondaryStat, and MaxSecondaryStat.

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Most parts classes ('''Armour''', '''Bombard''', '''Detection''', '''Fuel''', '''General''', '''Shield''', '''Speed''', '''Stealth''') only have a primary stat of capacity an no associated meter.<br />

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'''Troops''' and '''Colony''' part types have a primary capacity stat with associated Capacity meter.

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'''FighterHangar''' has a primary stat of capacity and a secondary of damage (number of boats, damage of each boat's attack) and the associated MaxCapacity and MaxSecondaryStat meters.

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Direct fire weapons (which only contains '''ShortRange''' currently) have a primary stat of damage and a secondary of shots.<br />

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shots determines how many times the weapon will fire each combat round.

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'''LaunchBay''' parts have a capacity stat with associated (Max)Capacity meters which specifies how many space boats may launch per combat turn.

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The meter value for a ship can be accessed using the ShipPartMeter part = "PART_NAME" meter = METER_TYPE object = SHIP_ID double complex variable. See above for which meters exist for which part class. Also note you can use Value(ShipPartMeter) to get the immediate/non-initial value. Defaults to 0.0

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In the source code, the ship meters and ship part meters are defined in the Ship::Ship constructor in universe/Ship.cpp

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===Species Specification===

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Species

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name = "NAME"

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description = "DESCRIPTION"

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gameplay_description = "GAMEPLAY_DESCRIPTION"

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Playable [optional -- defaults to not playable]

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Native [optional -- defaults to not native]

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CanProduceShips [optional -- defaults to cannot produce ships]

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CanColonize [optional -- defaults to cannot colonize]

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tags = ["TAG" "TAG" ...] [optional]

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foci = {FOCUSTYPE|[ [optional -- may be left out]

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FOCUSTYPE

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...

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]}

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preferredfocus = "FOCUS" [optional]

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effectsgroups = {EFFECTSGROUP|[ [optional -- may be left out]

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EFFECTSGROUP

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EFFECTSGROUP

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...

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]}

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environments = {PLANETTYPEENVIRONMENT [optional -- may be left out]

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PLANETTYPEENVIRONMENT

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PLANETTYPEENVIRONMENT

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...

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]}

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graphic = "GRAPHICFILENAME"

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Param Types:

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NAME string_constant

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DESCRIPTION string_constant

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GAMEPLAY_DESCRIPTION string_constant

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TAG string_constant

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FOCUSTYPE FocusType

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FOCUS string_constant

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EFFECTSGROUP EffectsGroup

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PLANETTYPEENVIRONMENT (see below)

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GRAPHICFILENAME string_constant

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* Species must have a unique name.

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* PLANETTYPEENVIRONMENT has format:

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type = PLANETTYPE environment = ENVIRONMENT

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with param types:

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PLANETTYPE PlanetType

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ENVIRONMENT PlanetEnvironment

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===ShipDesign Specification===

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ShipDesign

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name = "NAME"

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description = "DESCRIPTION"

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NoStringTableLookup [optional -- omission leaves default behavior]

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hull = "HULLTYPE"

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parts = [ [see note below]

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"PARTTYPE"

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"PARTTYPE"

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...

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]

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icon = "ICONFILENAME"

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model = "MODELNAME"

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Param Types:

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NAME string_constant

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DESCRIPTION string_constant

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HULLTYPE ShipHullType

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PARTTYPE string_constant

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ICONFILENAME string_constant

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MODELNAME string_constant

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* ShipDesign must have a unique name

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* PARTTYPE corresponds to the same ordered entry for each slot in HULLTYPE.

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** There must be the same number of PARTTYPEs as there are slots, but the PARTTYPE may be left empty ( "" ).

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** PARTTYPE must be compatible with the ShipSlotType for that slot.

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* ICONFILENAME and MODELNAME should be relative to the art directory.

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=Types and Expressions (ValueRefs)=

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In the Conditions and Effects below, there are parameters that specify details about how the condition or effect functions. These parameters can be specified as a constant number (eg. 5) or value (Blue), or can be variables that depend on the gamestate. Variables may refer to the Source, Target, RootCandidate or LocalCandidate objects (see below), a few independent values such as the number of the current game turn, or may refer to statistics about the gamestate that are calculated from multiple objects.

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==Source, Target, RootCandidate, LocalCandidate==

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ValueRefs, Conditions and Effects are evaluated in light of an automatically generated Scripting Context, which specifies one or more of a Source, Target, RootCandidate, and LocalCandidate. The way these get automatically generated depends on what content type is being evaluated.

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For an Effect, the Source object is the object to which the Effect is attached. For example, a building might have an effect that increases a planet's industry meter. When defining that building's effects, the building itself would be the Source object. Regarding using "Source" as a Condition, as is common when specifying a scope, see [[#Conditions|the Conditions Section below]].

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The Target object of an Effect is the object that the Effect is modifying. In an effect that modifies a planet's industry meter, the planet would be the Target object.

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The objects being tested by Conditions are candidates, and for reference within the scripts these are broadly divided into two types relating to the potentially multi-tiered nature of Conditions. Consider the following EffectsGroup scope condition:

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scope = WithinDistance distance = 5 condition = And [

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Planet

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OwnedBy TheEmpire RootCandidate.Owner

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Construction low = 0 high = LocalCandidate.TargetConstruction / 2

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]

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Here there are two sets of objects being matched:

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1) The objects actually being matched for the scope. These are objects within distance 5 of an object matched by the subcondition.

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2) The objects matched by the subcondition, which are used to evaluate the outer condition. These are planets that are owned by the same empire that owns the object matched in the outer condition, and that have less than half their own target construction.

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RootCandidate refers to the object being matched in the outer-most condition - WithinDistance in this case. This gives a way to refer to the object actually being matched by a big multi-part condition from one of the inner condition definitions, where the object being matched by a subcondition is likely not the same object being matched by the outer condition.

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LocalCandidate refers to the object being matched in whatever condition it is directly in - the Construction meter condition in this case. This gives a way to refer to the object being matched by the current condition, regardless of what other conditions are matching outside or inside the current condition.

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The RootCandidate and LocalCandidate may be used with the same types of variable references as for Source and Target.

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For the EffectGroups in Techs, the Location specification, BuildTime value and BuildCost value for content such as a BuildingType, ShipHull or ShipPart, the context Source is the EmpireSource for the empire currently under consideration; this is its Capital planet if it has one, otherwise some other object owned by the empire. The Target in this context is the potential production location (planet) for which the Location, BuildTime or BuildCost is being evaluated.

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For the Location specification for Specials, Source and Target are not set, but the LocalCandidate and RootCandidate references may be used.

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For EmpireStatistic ValueRefs, the scripting context only has a Source, which is the EmpireSource mentioned above.

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==Free/Independent Variables==

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There are some variables that may be used without referring directly to the Source, Target or candidate objects. The current free variables that may be referenced are those specifying the galaxy setup conditions, and one which provides the current game turn. These currently all provide an integer result. For galaxy setup variables, their underlying type is generally a specialized enumeration which for this purpose gets mapped to an integer corresponding to the order they get listed in the GalaxySetup screen. For example, most galaxy setup variables work with range [None, Low, Medium, High], which gets mapped to [0, 1, 2, 3]. (Many of those variables drop the None value, and so have a range of 1-3.) Current Max AI Aggressions range from 0 to 5. The current list of free variables is:

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Value (various, see below)

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GalaxySeed string

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CurrentTurn int

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GalaxyAge int

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GalaxyMaxAIAggression int

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GalaxyMonsterFrequency int

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GalaxyNativeFrequency int

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GalaxyPlanetDensity int

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GalaxyShape int

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GalaxySize int

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GalaxySpecialFrequency int

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GalaxyStarlaneFrequency int

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UniverseCentreX double

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UniverseCentreY double

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==Complex Variables==

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These variables are for values which need more than one parameter. These need at least one extra parameter to distinguish the right value and can not directly be accessed from an object. Instead you typically pass also the object ID (e.g. Source.ID, Target.DesignID) as parameter.

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PartsInShipDesign name = "PART_NAME" design = DESIGN_ID

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Returns the count of ship parts with the part name PART_NAME which are part of the ship design with the id DESIGN_ID. Will return zero if no such design exists or no such parts exist in the design.

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SpecialAddedOnTurn name = "SPECIAL_NAME" object = ID

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Returns the turn in the Special with the name SPECIAL_NAME was attached to the object ID. Will return zero if no such object exists or no such special was attached to the object (Note: this should be changed to a maximum turn number so SpecialAddedOnTurn <= CurrentTurn will be false if no special was attached to the object).

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SpecialCapacity name = "SPECIAL_NAME" object = ID

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Returns the capacity of the Special with the name SPECIAL_NAME attached to the object ID. Will return zero if no such object exists or no such special was attached to the object.

Returns the part meter value of a ship (as double). The meter value of the meter type METER_TYPE for the part with name PART_NAME of the ship with the id SHIP_ID.

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Note you can use Value(ShipPartMeter) in effects to get the immediate/non-initial value. Will return 0.0 if the ship does not exist, the ship design does not have such a part, or the part class does not have this kind of meter associated.

Object attributes are variables that are properties of the Source, Target, LocalCandidate, or RootCandidate objects. In combination these are also called "complex variables".

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Some of the attributes have changing values which are tracked and manipulated as a meter. Usually these attributes return the initial value of the meter (before effects are executed), but one can access the current value changed by other effects using a Value() expression, e.g. Value(Source.TargetResearch) will return the current value of the Source object's TargetResearch meter.

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===List===

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Here is a (currently incomplete) list of the attributes available (but not necessarily currently used in-game), and their types (more on types later):

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Age int the number of turns since the object was created

+

CreationTurn int the turn the object was created

+

ID int +++

+

Name string

+

LastTurnBattleHere int the last turn a battle was in the system or the system which contains this object

<br>+ The valid values for these types are listed after the corresponding conditions below. These values may change however, so for the most up-to-date list, it may be necessary to consult the FreeOrion source code.

+

<br>++ Owner will return -1 if there are no owners (such as for a roaming space monster or unexplored system)

+

<br>+++ This is the unique integer ID used to identify an object internally within FreeOrion.

+

<br>++++ This is the unique integer ID used to identify a ship design.

+

<br> m This is tracked using a meter. There might be a connected target meter or max meter

+

<br>mm This is tracked using a max meter.

+

<br>tm This is tracked using a target meter.

+

<br>! While the code distinguishes between ProdCenter and PopCenters there is currently no overlap it is always a Planet ~~The types returned by ObjectType have some overlap. For instance, a Planet is also a PopCenter and a ProdCenter. In this case, Planet is returned before PopCenter or ProdCenter, since if you see a Planet, you know it is a ProdCenter, but seeing a ProdCenter, you have no idea if it is a Planet or something else that produces goods or resources, for instance a mining outpost. This principle guides the order in which type is determined when ObjectType is used.~~

+

+

The reference for the attributes is the file universe/ValueRef.cpp

+

+

==Value==

+

+

As a special case, there is a utility variable available that is used like a free variable, but actually refers to what is being modified by an effect:

+

+

Value double, int, string, PlanetSize, PlanetType, StarType

+

+

The value of "Value" is the initial value (before the current effect acts) of whatever is being set. For example, in a SetStealth effect, "Value" would return the same as "Target.Stealth". For SetPlanetType, "Value" would return the same as "Target.PlanetType".

+

+

The type returned by "Value" depend on the type of effect in which it is used. For meter-setting effects Value will be a double. For SetPlanetSize, it will be a PlanetSize, and similarly for PlanetType, PlanetEnvironment, StarType. For setting a planet's species, Value will be a string.

+

+

Do not confuse this with the Value() expression, which is used to get the current value of a meter using a complex variable.

+

+

==Statistics==

+

+

Statistics are values calculated from a sampling of objects in the game universe, which may or may not include the Source and Target objects.

+

+

====List====

+

+

The available statistical calculations that can be performed on the property values of objects matching the sampling condition are:

+

+

If - Returns 1 if at least one object matches the selection condition, or 0 otherwise

+

Count - Returns the number of objects that match the selection condition

+

UniqueCount - Returns the number of unique values of the property are present among objects that match the selection condition

+

Sum - Returns the sum of property values of objects that match the selection condition

+

Mean - Returns the arithmetic mean of property values

+

RMS - Returns the square root of the arithmetic mean of the squares of the property values

+

Mode - Returns the most common property value

+

Max - Returns the largest property value

+

Min - Returns the smallest property value

+

Spread - Returns the difference between the largest and smallest property values

+

STDEV - Returns the standard deviation of the property values

+

Product - Returns the product of multiplying all the property values together

+

+

Mode may be used for any type of parameter, including enumerated types like PlanetSize and double or int or string. The other statistic types may be used only for parameters that are int or double. If and Count may be used without specifying a property value.

+

+

===Use===

+

+

====Constants====

+

In item descriptions, parameter values such as LOW, HIGH, or NUMBER may be simple numbers, like 5 or 10, in which case all objects with the appropriate meter are treated the same by Turn.

+

+

====Variables====

+

Parameter values may also be defined in terms of attributes (or "properties") of the Source, RootCandidate, LocalCandidate or Target object. In these cases, different objects may be differently matched or not, if the property used differs between them.

+

+

Object attributes can be referenced on the source or target object, but not alone. So "Source.ID" and "Target.PlanetSize" are legal variables, but "PlanetEnvironment" in isolation is not.

+

+

Parameter values may also be defined in terms of the free variables mentioned above that are not associated with a particular object. In this case, the variable name is used without any object reference; for example, "CurrentTurn" returns the current game turn.

+

+

Parameter values for meter-altering effects may also refer to "Value" which is equivalent to referring to the meter of the target object that is being altered, depending which meter-setting effect is being used.

+

+

In addition, an object's containing object, if one exists, may be used in a variable. For instance, if the source is a planet, "Source.System.StarType" represents the star type of the source's system. Planet may also be used in a similar fashion, as in "Target.Planet.PlanetEnvironment".

+

+

Nonsensical combinations of Target, Source, Planet, System, and the above attributes are allowed, but will always return 0 for numeric values, and a special value representing an invalid value for enumerated type values. The special invalid value is guaranteed not to match the value of any actual object.

+

+

For example, if the source object is a System, Source.System.StarType will always return an invalid Star Type.

+

+

Similarly, Target.System.Industry makes no sense (since industry meters meters exist for Planets but not Systems), and so will return the double value 0.0.

+

+

====Statistics====

+

Parameter values may also be defined in terms of statistics calculated from the gamestate. A statistic returns a value based on the specified property, calculation and a condition to select objects in the game Universe.

+

+

In any place where a constant or variable could be specified, a statistic may be used instead. The format for a statistic calculation is:

+

+

Statistic STATISTIC_TYPE value = VALUE condition = SAMPLING_CONDITION

+

+

For example, to calculate the sum of all planets' populations,

+

Statistic Sum value = LocalCandidate.Population condition = Planet

+

+

The result would return a double value, which will be used just as if a constant like 42.4 had been specified, or a variable like Target.Population had been specified.

+

+

==Types==

+

+

The "double" type listed above, is a double-precision floating point number, which is more or less any real number in the range [-10^300, 10^300]. The "int" type is an integer number, which is basically any whole number in the range [-2*10^9, 2*10^9]. The other types are enumerated types, with specific values. Each such value has a string associated with it, for instance the first valid StarType is Blue.

+

+

In the Conditions and Effects below, certain parameters have types. It is illegal to provide a parameter of the wrong type, and it will result in a thrown exception (a purposeful crash of FreeOrion). There is one major exceptions to this. It is legal to provide a int value for any parameter of any type. This is mainly to support easy expression syntax, which is the next thing that needs to be addressed.

+

+

Instead of providing a singe variable or constant value (such as 3.14, 5, or STAR_BLUE), you can instead provide an arithmetic expression. Legal expressions may contain parentheses, +, -, *, / and ^ (for exponentiation). The - operator can be binary as in "3 - 4", or unary as in "-Source.MaxHealth". Whitespace (spaces, tabs, and newlines) is ignored. Expressions may be arbitrarily complex. The type of the entire expression must match the type of the parameter for which it is intended. For instance, it is illegal to supply "1 + 3.14" as a value for an int-type parameter, since 3.14 is not an int. As mentioned before, though, it is legal to supply "STAR_BLUE + 1" as a value for a StarType parameter, since integers are always ok.

+

+

Note that since arbitrarily complex expressions are allowed in Effects, and multiple Effects may affect a single target in a single turn, the order in which the Effects are applied to the target may matter. For instance, if Effect A sets the current industry meter to "Target.Industry + 20", and Effect B sets the current industry meter to "Target.Industry * 3", the answer could be X * 3 + 20 or (X + 20) * 3, depending on the order of execution. To minimize this, and in keeping with the guidelines for Effects in general, such Effects should have small magnitude, which will make the problem largely disappear. For instance, if "Target.Industry + 3" and "Target.Industry * 1.05" are used instead, the difference between X * 1.05 + 3 and (X + 3) * 1.05 is a negligible 0.15.

+

+

Note that some of the parameters in the Conditions and Effects below ask for a certain type, sometimes a type-expression. Those parameters that do not explicitly allow type-expressions cannot handle them.

+

+

==Value==

+

+

The Value parameter for a statistic can be practically any kind of ValueRef, including complex expressions. The one exception that comes to mind is that attempting to use a statistic as the Value for another statistic has had parsing problems which may not yet be fully resolved.

+

+

=Conditions=

+

+

The syntax {a|b|c} below indicates a choice of values, exactly one of which must be selected. The brackets and vertical lines are not legal to use themselves.

+

+

{a|[a b c ...]} indicates that a single item may be specified ( a ), or multiple items in a list ( [a b c ...] ).

+

+

"low = ", "high = ", etc., indicates an *optional* parameter name. All parameters must appear in the order indicated, so the names are not necessary to indicate which value is meant for which parameter. The name may be included, however (except for with the And, Not and Or conditions, which do not have or allow such parameter names).

+

+

==General==

+

+

All

+

+

Matches all objects.

+

+

+

Source

+

+

Matches the Source object.

+

+

+

Target

+

+

Matches the target object of an effect. This can be used within effect definitions, but not within scope or activation condition definitions, as when those conditions are evaluated, the target object hasn't yet been determined.

+

+

+

Turn low = LOW high = HIGH

+

+

Matches objects if the current game turn is greater than or equal to LOW and less than HIGH.

+

+

+

NumberOf number = NUMBER condition = CONDITION

+

+

Matches at most NUMBER objects that match CONDITION. If fewer than NUMBER objects match CONDITION, all such objects are matched. If more than NUMBER objects match CONDITION, NUMBER such objects are randomly selected and matched.

These variants of NumberOf take a SORTKEY argument which is used to sort the objects matching the CONDITION before the elements get selected. The SORTKEY is a double valueref (e.g. such as LocalCandidate.Happiness).

+

MinimumNumberOf will select and match (up to) NUMBER objects which have the smallest SORTKEY value of all matching objects.

+

MaximumNumberOf will select and match (up to) NUMBER objects which have the highest SORTKEY value of all matching objects.

+

ModeNumberOf will select and match (up to) NUMBER objects which have the most frequent values of all matching objects' SORTKEY values (e.g. you could a match a number of planets with the most common defense meter value).

+

+

+

Number low = LOW high = HIGH condition = CONDITION

+

+

Matches all objects if the number of objects that match CONDITION is greater than or equal to LOW and less than HIGH. Objects matched may or may not themselves match CONDITION.

+

+

+

Random probability = PROB

+

+

Matches objects with a probability of PROB. That is, objects have a probability of PROB of being matched.

Matches objects where the empire with the indicated id EMPIRE (or any empires if none is specified) have within the indicated range (LOW to HIGH inclusive) of the indicated type of production item with the indicated name or design ID (NAME or DESIGN ID) and TYPE (Building or Ship). The count used to assess LOW and HIGH takes into account the element blocksize.

+

+

==Planet / Star==

+

+

Planet type = {TYPE|[TYPE0 TYPE1 TYPE2 ...]}

+

+

Matches objects that are or are contained by planets that have the indicated type.

+

+

Types are:

+

Swamp

+

Toxic

+

Inferno

+

Radiated

+

Barren

+

Tundra

+

Desert

+

Terran

+

Ocean

+

Gaia

+

Asteroids

+

GasGiant

+

+

+

Planet size = {SIZE|[SIZE0 SIZE1 SIZE2 ...]}

+

+

Matches objects that are or are contained by planets that are the indicated size.

+

+

Sizes are:

+

Tiny

+

Small

+

Medium

+

Large

+

Huge

+

Asteroids

+

GasGiant

+

+

+

Planet environment = {ENV|[ENV0 ENV1 ENV2 ...]}

+

+

Matches objects that are or are contained by planets that have the indicated environment.

+

+

Environments are:

+

Uninhabitable

+

Hostile

+

Poor

+

Adequate

+

Good

+

+

+

HomeWorld

+

name = {SPECIES|[SPECIES0 SPECIES1 ...]} [optional -- may be left out]

+

+

Matches planets that are homeworlds to playable species. If no species are specified, the homeworld of any species will be matched.

+

+

SPECIES the name of a species in the game, as defined in a species definition file

+

+

+

Capital

+

+

Matches planets that are capitols of an (any) empire. Use in combination with OwnedBy for a specific empire's homeworld.

+

+

+

Star type = {TYPE|[TYPE0 TYPE1 TYPE2 ...]}

+

+

Matches objects that are or are contained by systems that have the indicated star type.

+

+

Types are:

+

Blue

+

White

+

Yellow

+

Orange

+

Red

+

Neutron

+

BlackHole

+

+

==Infrastructure / Focus==

+

+

Focus focus = {FOCUS|[FOCUS0 FOCUS1 FOCUS2 ...]}

+

+

Matches planets that have the indicated focus or any of the indicated foci.

+

+

FOCUS or FOCUS# are strings. Each species may have a different set of foci available, but typical focus options include "FOCUS_GROWTH", "FOCUS_INDUSTRY", "FOCUS_LOGISTICS", "FOCUS_PROTECTION", "FOCUS_RESEARCH", and "FOCUS_STOCKPILE"

+

+

To check if a given focus (FOCUS_RESEARCH in the below example) is simply available at a planet (even if not actually selected), the following check can be used:

For reference the focus are defined in file default/scripting/species/common/focus.macros

+

+

==MeterValue==

+

+

TargetPopulation low = LOW high = HIGH

+

TargetIndustry low = LOW high = HIGH

+

TargetResearch low = LOW high = HIGH

+

TargetTrade low = LOW high = HIGH

+

TargetConstruction low = LOW high = HIGH

+

MaxFuel low = LOW high = HIGH

+

MaxShield low = LOW high = HIGH

+

MaxStructure low = LOW high = HIGH

+

MaxDefense low = LOW high = HIGH

+

Population low = LOW high = HIGH

+

Industry low = LOW high = HIGH

+

Research low = LOW high = HIGH

+

Trade low = LOW high = HIGH

+

Construction low = LOW high = HIGH

+

Fuel low = LOW high = HIGH

+

Shield low = LOW high = HIGH

+

Structure low = LOW high = HIGH

+

Defense low = LOW high = HIGH

+

Supply low = LOW high = HIGH

+

Stealth low = LOW high = HIGH

+

Detection low = LOW high = HIGH

+

Starlanespeed low = LOW high = HIGH

+

HasSpecialCapacity name = "SPECIAL_NAME" low = LOW high = HIGH

+

HasSpecialSinceTurn name = "SPECIAL_NAME" low = LOW high = HIGH

+

+

Matches objects with the appropriate meter values that are greater than or equal to LOW and less than or equal to HIGH. That is, LOW specifies the lowest allowed value of the meter, and HIGH specifies the highest allowed value. Either of the LOW and HIGH parameters may be omitted, in which case there is no limit on the meter value in that direction. For example, if only LOW is specified, there is no upper limit on the allowed meter value.

+

+

The HasSpecialCapacity uses the capacity meter of the special given as string name. The HasSpecialSinceTurn queries the turn a special was first set on an object.

Matches objects owned by (OwnedBy) an empire with the indicated affiliation to the indicated id EMPIRE. EMPIRE may be omitted with using AnyEmpire, which will match objects owned by any empire, regardless of what EMPIRE is specified (or not). Typically EMPIRE is specified as a function of an object, such as Source.Owner, however a constant integer such as 2 may also be specified.

+

+

+

OwnerFoodStockpile low = LOW high = HIGH

+

OwnerMineralStockpile low = LOW high = HIGH

+

OwnerTradeStockpile low = LOW high = HIGH

+

+

Matches objects with exactly one owner, whose owner's stockpile of the appropriate resource is greater than or equal to LOW and less than or equal to HIGH.

+

+

+

OwnerHasTech name = "NAME"

+

+

Matches objects with exactly one owner, whose owner has the tech NAME.

+

+

Note: This is useful for refinements of technologies, where a refinement tech is indicated by NAME in an effects group of the item being refined.

+

+

+

VisibleToEmpire empire = {EMPIRE|[EMPIRE0 EMPIRE1 EMPIRE2 ...]}

+

+

Matches objects that are visible to the indicated empire(s).

+

+

+

ProducedByEmpire empire = EMPIRE

+

+

Matches buildings or ships produced by the empire with id indicated by EMPIRE. Typically EMPIRE is specified as a function of an object, such as Source.Owner, however a constant integer such as 2 may also be specified. Note that ownership and who produced an object aren't necessary the same, particularly for buildings, which may be captured with planets from other empires.

+

+

==Ship Design==

+

+

Design name = "NAME"

+

+

Matches ships that have a design generated from the predefined designs in ship_designs/ or monster_designs/.

+

+

Design design = DESIGNID

+

+

Matches ships that have the specified ship design ID. Most likely this would be Source.DesignID

+

+

DesignHasHull name = "NAME"

+

+

Matches ships that have the indicated hull in their design.

+

+

DesignHasPart low = LOW high = HIGH name = "NAME"

+

+

Matches ships that have >= LOW and < HIGH of the part NAME in their design.

+

+

DesignHasPartClass low = LOW high = HIGH class = CLASS

+

+

Matches ships that have >= LOW and < HIGH of parts of the indicated PartClass in their design.

+

+

Armed

+

+

Matches ships that have weapons.

+

+

Monster

+

+

Matches space monsters.

+

+

==Galaxy Map Position==

+

+

WithinDistance distance = DISTANCE condition = CONDITION

+

+

Matches objects that are within the indicated Euclidean direct-line DISTANCE of any objects that matches CONDITION. The matched objects may or may not themselves match CONDITION.

+

+

+

WithinStarlaneJumps jumps = JUMPS condition = CONDITION

+

+

Matches objects that are within the indicated number of starlane jumps (crossings from one star to the next) of any objects that matches CONDITION. The matched objects may or may not themselves match CONDITION.

+

+

+

Stationary

+

+

Matches objects that are not moving. The only objects that move are fleets and ships. Objects are not stationary if they are going to move, so fleets ordered to move are not stationary, but fleets that arrive in a system are stationary on the turn after they arrive.

+

+

ResupplyableBy empire = EMPIRE

+

+

Matched objects should be in systems where the empire with id EMPIRE can provide fleet supply.

+

+

ResourceSupplyConnected empire = EMPIRE condition = CONDITION

+

+

Matched objects should be in systems connected by resource sharing lines for the empire with id EMPIRE to at least one object that matches the sub-condition CONDITION. Objects outside systems shouldn't be matched, regardless of whether they're on a starlane that is connected to an object that matched the sub-condition.

+

+

==Conditional==

+

+

Conditional conditions are variants of some kind of "if". The only conditional condition we have currently is OrderedAlternativesOf, in some cases one can use the If statistic in ValueRef statements to get conditional results.

+

+

The OrderedAlternativesOf provides the ability to conditionally match the objects of the first condition inside of it which matches at least one local candidate.

+

An example from FT_HANGAR_1 (Note that COMBAT_TARGETS_VISIBLE_ENEMY has to be repeated inside each single tier condition)

Matches objects that match at least one, or more, of the indicated subconditions.

+

+

+

Not CONDITION

+

+

Matches objects that do not match CONDITION.

+

+

==Notes==

+

+

===Implicit ContainedBy===

+

+

Some Conditions that match an object's containing object will be returned, even though they at first seem to be nonsensical. For instance, if the target object is a Planet, StarType will match the type of the System in which the target is located. This means that StarType will match all objects in all Systems with the given star type, and the Systems themselves. Similarly, all objects on all Planets (and the Planets themselves) that match a PlanetType, PlanetSize, or PlanetEnvironment will be matched. This has an important implication; if you want all Systems with blue stars, you should use

+

+

And [

+

Star type = Blue

+

System

+

]

+

+

If you want all Ships in Systems with blue stars, you should use:

+

+

And [ Ship Star type = Blue ]

+

+

===And & Or Efficiency===

+

+

The And and Or Conditions are designed to work as efficiently as possible, by only searching the objects that have not already been matched. So it is always best to put the most restrictive Condition first in an And Condition's list of subconditions.

+

+

For instance, if "Star type = Blue" matches about 1000 objects,

+

And [ Source Star type = Blue ]

+

will be about 1000 times faster than

+

And [ Star type = Blue Source ]

+

This is because the former only has to look at the match from Source to see if it also is (or is inside of) a blue-starred System, whereas that latter has to look through the 1000 matches of objects that are or are in blue-starred systems, to see if any of them also matches Source.

+

+

=Effects=

+

+

==SetMeter==

+

+

# on planets

+

SetTargetConstruction value = VALUE # not really in use

+

SetTargetHappiness value = VALUE

+

SetTargetIndustry value = VALUE

+

SetTargetPopulation value = VALUE

+

SetTargetResearch value = VALUE

+

SetTargetTrade value = VALUE # not in use

+

SetMaxDefense value = VALUE

+

SetMaxSupply value = VALUE

+

SetMaxStockpile value = VALUE

+

SetConstruction value = VALUE # not really in use

+

SetDefense value = VALUE

+

SetHappiness value = VALUE

+

SetIndustry value = VALUE

+

SetPopulation value = VALUE

+

SetResearch value = VALUE

+

SetSupply value = VALUE

+

SetTrade value = VALUE # not in use

+

SetSize value = VALUE

+

+

# on planets and ships

+

SetMaxShield value = VALUE

+

SetMaxTroops value = VALUE

+

SetDetection value = VALUE

+

SetShield value = VALUE

+

SetStealth value = VALUE

+

SetTroops value = VALUE

+

+

# on ships

+

SetMaxFuel value = VALUE

+

SetMaxStructure value = VALUE

+

SetFuel value = VALUE

+

SetSpeed value = VALUE

+

SetStructure value = VALUE

+

+

Param Type:

+

VALUE double

+

+

Sets the appropriate meter to VALUE.

+

+

* If the target of the Effect does not have the requested meter, nothing is done.

+

* Typically, meter-setting effects do so by adding or subtracting form the same meter value of the Target. For example,

+

+

SetTargetResearch Target.TargetResearch + 5

+

+

or

+

+

SetHealth Value - 10

+

+

The value "Value" always refers to the present value of the meter being set, allowing incremental changes to meter values without the cumbersome use of references to the Target such as "Target.FoodConsumption" (for the Target's food consumption meter) which would instead be just "Value" when using the SetFoodConsumption effect.

+

+

When a "max" (eg. MaxStructure) or "target" (eg. TargetPopulation) meter value, or another meter for which there is no associated "max" or "target" meter (eg. Stealth), the change is non-persistent. This means that every turn, the meter is reset to 0, and all effects must re-act on the meter for it to retain a consistent value. If on a subsequent turn, the effect does not at on that target, the meter value will return to its previous value (or whatever value all other effects acting on it produce).

+

+

When a meter (eg. Structure) has an associated "max" or "target" meter (eg. MaxStructure), the meter value IS persistent. Repeatedly applying the same effect every turn will accumulate. If an effect reduced an object's Health meter by -2 every turn, the 2nd turn would have a net -4 reduction, the 3rd turn would have a net -6 reduction, etc. If an effect alters such a meter once, then does not act again, the meter stays reduced, until other effects increase or decrease it, or it increases or decreases itself over time towards its associated target or max value.

+

+

==SetShipPartMeter==

+

+

Acting on ships:

+

SetMaxCapacity (set capacity max meter)

+

SetMaxDamage (set capacity max meter - this may do the wrong thing for hangar parts)

+

SetMaxSecondaryStat (set secondary capacity max meter)

+

SetCapacity (set capacity meter)

+

SetDamage (set capacity meter - this may do the wrong thing for hangar parts)

+

SetSecondaryStat (set secondary capacity meter)

+

+

==SetOwnerCapitol==

+

+

SetOwnerCapitol

+

+

Sets the target object to be the capitol of its owner's empire. If the target is not a planet, or is not owned by a single empire, nothing is done.

+

+

==SetPlanetType==

+

+

SetPlanetType type = TYPE

+

+

Param Type:

+

TYPE PlanetType

+

+

Sets the planet type of the target to TYPE.

+

+

* Has no effect on non-Planet targets.

+

* Changing type from Asteroids or GasGiant to something else will also change its size to Tiny or Huge, respectively.

+

* Changing type to Asteroids or GasGiant will also cause the size to change to Asteroids or GasGiant, respectively.

+

+

==SetPlanetSize==

+

+

SetPlanetSize size = SIZE

+

+

Param Type:

+

SIZE PlanetSize

+

+

Sets the planet size of the target to SIZE.

+

* Has no effect on non-Planet targets.

+

* Changing the size of a Asteroids or GasGiant planet will also change its type to Barren.

+

* Changing size to Asteroids or GasGiant will also cause the type to change to Asteroids or GasGiant, respectively.

+

+

==SetOwner==

+

+

SetOwner empire = EMPIRE

+

+

Param Type:

+

EMPIRE int

+

+

Sets empire EMPIRE_ID as the owner of the target.

+

* Has no effect if EMPIRE_ID was already the owner of the target object.

+

+

==CreatePlanet==

+

+

CreatePlanet type = TYPE size = SIZE

+

+

Param Types:

+

TYPE PlanetType

+

SIZE PlanetSize

+

+

Creates a new planet at the location of the target object. If the target object is not located in a system, nothing is done. If there are no free orbit slots at the target object's system, nothing is done.

+

+

==CreateBuilding==

+

+

CreateBuilding name = NAME

+

+

Param Types:

+

NAME string

+

+

Creates a new building at the location indicated by the target object. If the target object is not a planet, nothing is done.

+

+

==CreateShip==

+

+

CreateShip

+

designname = "NAME"

+

empire = EMPIREID

+

species = "SPECIES"

+

+

ParamTypes

+

NAME string_constant

+

EMPIREID int_constant

+

SPECIES string_constant

+

+

Creates a new shipat the location of the target object. The design of the new ship is indicated by the NAME parameter, which looks up the design in premade_ship_designs.txt in the default folder. EMPIREID is the id of the empire who should own the newly created ship, which is probably the id of something related to the source or target objects. SPECIES is the name of the species which should crew the newly created ship, which can be something related to target or source objects, or an explicit species name.

+

+

==Destroy==

+

+

Destroy

+

+

Destroys the target object.

+

+

* The Destroy effect will not destroy a System object, although any other objects in or outside a system can be destroyed.

+

* Destroy effects are executed after all other effects.

+

* Destroying a fleet will destroy its ships.

+

* Destroying all the ships in a fleet will destroy the fleet.

+

* Destroying a planet will destroy its buildings.

+

+

==AddSpecial==

+

+

AddSpecial name = "NAME"

+

+

Param Type:

+

NAME string_constant

+

+

Adds the Special with the name NAME to the target object.

+

* Note that using a wrong NAME/a NAME for which no special is specified is possible but will lead to strange behaviours

+

* You can retrieve the turn a Special was added using the SpecialAddedOnTurn complex variable

+

+

==RemoveSpecial==

+

+

RemoveSpecial name = "NAME"

+

+

Param Type:

+

NAME string_constant

+

+

Removes the Special with the name NAME to the target object.

+

* Has no effect if no such Special was already attached to the target object.

+

+

==SetSpecialCapacity==

+

+

SetSpecialCapacity name = "NAME" capacity = NUMBER

+

+

Param Type:

+

NAME string_constant

+

NUMBER double (ValueRef)

+

+

Sets the capacity of Special with the name NAME to the given NUMBER.

+

* Adds the Special if no such Special was already attached to the target object.

+

* If such a Special was attached, this won't change the since turn value (queried by HasSpecialSinceTurn)

+

* Object candidates can be filtered using the HasSpecialCapacity condition

+

* The special's capacity value can be retrieved using the SpecialCapacity complex variable

+

+

==SetStarType==

+

+

SetStarType type = TYPE

+

+

Param Type:

+

TYPE StarType

+

+

Sets the star type of the target to TYPE.

+

* Has no effect on non-System targets.

+

+

==MoveTo==

+

+

MoveTo location = CONDITION

+

+

Param Type:

+

LOCATION Condition

+

+

Moves the target object to the location of one of the objects matched by LOCATION

+

* If no objects match the location condition, nothing is done.

+

* If more than one object matches the location condition, one object is chosen by the condition

+

* If the target object is a ship and the location object is a fleet or a ship (in a fleet) owned by the same empire, the ship is inserted into the fleet.

+

* If the target object is a ship and the location is not a fleet into which the ship can be inserted, a new fleet is created for the ship a the new location.

+

* If the target object is a ship and its location is the same system but not a different fleet, nothing is done and the ship is left in its original fleet.

+

* If the target object is a fleet and its location is a fleet or ship outside a system, and a fleet is moved to or created at the target location, the fleet will be moving to the same system as the taget object fleet.

+

* If the target object is a building and the location object is a planet or a building on a planet, the building is added to the planet.

+

* If the target object is a building and the location is not a planet or on a planet, nothing is done.

+

* If the target object is a planet and the location object is not a system or in a system, nothing is done.

+

* If the target object is a planet and the location system has no empty orbit slots, nothing is done.

+

* If the target object is a system, nothing is done.

+

* Any target object moved to the location of a system will be inserted into that system.

+

+

==Techs==

+

+

GiveEmpireTech name = "NAME"

+

GiveEmpireTech name = "NAME" empire = EMPIRE

+

+

Param Type:

+

NAME string_constant

+

EMPIRE integer ID of empire (such as Target.Owner which is the default if this parameter is omitted).

+

+

GiveEmpireTech gives the indicated empire the indicated tech. After this, the result should be the same as if the empire had researched that tech.

SetEmpireTechProgress sets the amount of research points (RP) the indicated empire has accumulated towards researching the indicated tech (limited to between 0 and the total RP cost of the tech).

+

+

==Victory==

+

+

Victory reason = "REASON"

+

+

Param Type

+

REASON string_constant

+

+

Victory causes the owner of the target object to win the game. Losing human players (which is any player who has not won on the turn a player wins) are ejected from the game. The string REASON is d_constantisplayed in a popup to all players, with the name of the winning empire inserted as the %1% parameter to the string.

+

+

==AddStarlanes and RemoveStarlanes==

+

+

AddStarlanes endpoint = CONDITION

+

RemoveStarlanes endpoint = CONDITION

+

+

Param Type

+

CONDITION condition

+

+

AddStarlanes adds starlanes between the target system and any system containing an object that matches CONDITION. RemoveStarlanes removes starlanes between the target system and any system containing an object that matches CONDITIONS. Adding a starlanes where one already exists, or removing a starlane wher none exists does nothing.

+

+

==MoveTo==

+

+

MoveTo destination = CONDITION

+

+

Param Type

+

CONDITION condition

+

+

MoveTo moves the target object to the location of the / one of the objects matched by the CONDITION parameter.

+

+

==SetDestination==

−

==Duration==

+

SetDestination destination = CONDITION

−

* Permanent The item remains unlocked for the entire game.

+

−

* Life of Effect When the effect is destoyed, the item returns to being locked. For example, if a buiding that opens up a special part of the tech tree is lost, that branch of the tree would be closed for research.

+

+

Param Type

+

CONDITION condition

−

=Examples=

+

SetDestination sets the travel route of the target fleet to be the shortest path for the target to move to an object that matches the CONDITION parameter. If multiple objects match CONDITION, one is chosen. If the target fleet can't move to the chosen object, nothing is done. The shortest path for the object may depend on the empire that owns it (if any).

−

==Universal University==

+

==SetAggression==

−

(building)

+

−

The Universal University offers a quality education to budding young science geeks.

+

−

The U.U. has two effects:

+

SetAggressive

+

SetPassive

−

===Advanced Education===

+

SetAggressive marks a fleet as aggressive, meaning it will block enemy supply, and engage any enemy fleets or planets in its system. SetPassive marks a fleet as passive, meaning it will not block supply or initiate combat. Remaining passive may be useful for staying hidden in a system (if stealthy) or to make non-aggressive monster types not attack player fleets.

−

* Scope: Empire

+

−

* Affliation: Exclusive

+

−

* Meter: Science

+

−

* Type of Modification: Additive

+

−

* Value of Modification: +1

+

−

* Stacking: Does not stack

+

−

* Focus Condition: None

+

−

* Infra Condition: 5

+

−

* Enviro Condition: None

+

−

* Description: +1 Science to Developed worlds from Universal University

+

−

===Science Inspiration===

+

==SetSpecies==

−

* Scope: Sector

+

−

* Affliation: Friends

+

−

* Meter: Science

+

−

* Type of Modification: Additive

+

−

* Value of Modification: +1

+

−

* Stacking: Does not stack

+

−

* Focus Conditions: Primary

+

−

* Infra Conitions: 5

+

−

* Enviro Condidtion: None

+

−

* Description: +1 Research to Developed Science worlds, due to a nearby Universal University

+

−

==Ocean Survival==

+

SetSpecies name = "NAME"

−

(Tech)

+

−

Your empire has developed methods of surviving and exploiting Ocean worlds.

+

−

Two effects:

+

Param Type

−

===Floating Platforms===

+

NAME string_constant

−

* Scope: Empire

+

−

* Affliation: Exclusive

+

−

* Meter: Enviroment

+

−

* Type of Modification: Additive

+

−

* Value of Modification: +2

+

−

* Stacking: Does not stack

+

−

* Focus Condition: None

+

−

* Infra Condition: None

+

−

* Enviro Condition: Ocean

+

−

* Description: +2 Enviroment from Ocean Survival

+

−

===Fish n' Chips===

+

SetSpecies sets the species of the target ship or planet to the indicated species NAME.

−

* Scope: Empire

+

−

* Affliation: Exclusive

+

−

* Meter: Farming

+

−

* Type of Modification: Additive

+

−

* Value of Modification: +1

+

−

* Stacking: Does not stack

+

−

* Focus Condition: Secondary

+

−

* Infra Condition: 1

+

−

* Enviro Condition: Ocean

+

−

* Description: +1 Food to Ocean Farming Worlds from Ocean Survial

+

−

==Hostile Microcobes==

+

==SetVisibility==

−

(Planet Special)

+

−

Nasty little one celled horrors have proven resistant to extermination.

+

−

Two effects:

+

The following details for this Effect correspond to the modifications currently proposed in [https://github.com/freeorion/freeorion/pull/1764 PR 1764], please note some constraints/complications regarding priority and timing of evaluation as discussed in the PR.

AFFILIATION optionally specifies an empire affiliation. Defaults to TheEmpire if an empire ID is specified, or AnyEmpire if no empire ID is specified.

+

EMPIRE optionally specifies an Int ValueRef specifying an empire ID, which is used with the affiliation to determine which empire's visibility/ies to set. Defaults to an invalid empire ID if none is specified, which will work with affiliations that aren't relative to a particular empire.

+

VALUEREF A Visibility type ValueRef, can include expressions like max(Value, V) where Value refers to the current visibility

+

CONDITION optionally condition specifies the object(s) whose visibility is to be set. If no condition is specified, the effect target object's visibility is set.

+

==Effect Evaluation & Application Ordering==

−

=Future Effects=

+

Effects are evaluated and then applied while processing a FreeOrion turn. When this happens, <i>all</i> EffectsGroups' activation and scope conditions are evaluated before <i>any</i> effects are applied.

−

There will be more Effect Classes in future versions, possibly including:

+

−

==Modify ShipPart==

+

The order of effects' application is determined primarily by their specified Priority (beginning at 0).

−

A modification of ship parts, improving or penalizing various stats.

+

−

This is meant for techs that refine parts, or buildings that give bonuses to certain unit types.

+

For EffectsGroups sharing the same Priority number their secondary ordering is determined by their source/cause, as follows: effects from Species, then effects from Specials, then effects from Techs, then effects from Buildings, then effects from Ship Hulls, then effects from Ship Parts.

+

The order of execution of Effects within these groups is deterministic, though not controllable.

−

==Modify Infrastructure==

+

Multiple effects scripted into the same item will be evaluated in the order in which they appear.

−

Directly effects the infrastructure (ie, Current Meter) of a planet, rather than the Max Meter. Useful for events like bombings or earthquakes.

+

−

==Events style effects==

+

[[Category:Scripting]]

−

Like the multiple choice events in EU2. If the game has 'em, it will probably require some kind of scripting.

+

Revision as of 23:23, 29 September 2019

This page augments the FOCS Scripting Tutorial (which should be reviewed first) and describes in more detail the scripting language used to describe much of the content of FreeOrion. This language is sometimes referred to as the FreeOrion Content Script, or "FOCS". Scripted content includes scripted descriptions of technology, buildings, and specials. These content files are text files, but some of them include special characters and therefor when editing them a somewhat more advanced editor is necessary. For example, on Windows, the Notepad and Wordpad editors can cause trouble, but the third party NotePad++ editor should be fine. An added benefit of using NotePad++ is that one of our contributors has made an add-on to help with the FOCS syntax.

The files in these directories contain descriptions of individual entries of their respective contents. buildings/ contains files with "BuildingType" descriptions (see below). specials/ contains "Special" descriptions. techs/ contains tech category and tech descriptions. When there are multiple entries in a single file, the ordering of entries in the files do not matter. Files can be organized into sub-directories as needed, for example ship_parts might contain a directory for weapon entries.

The primary building blocks used to specify the above types of FreeOrion content are ValueRefs (value references), Conditions, and EffectsGroups (which contain Effects and Conditions). Effects change the game state and thereby give buildings, techs and specials their in-game purpose. Conditions act to filter a starting set of objects to a smaller set (which might sometimes wind up being one or none). In EffectsGroups Conditions determine if (the activation condition) and on what (the scope condition) effects act. Conditions also have a few other uses, such as determining where buildings or ship parts or hulls can be produced, and where species focus settings can be used; they are also used within some of the more advanced ValueRefs. ValueRefs provide values used by the other portions of the script. Sometimes that might be a simple constant, like three, which the scripter would simply write as "3". Other times that might be a dynamic value such as the current game turn number, scripted as "CurrentTurn". In other cases that might be something much more complex, such as the number of monsters within two starlane jumps of a given system; the syntax for such value references is described farther below.

Scripting Format

In FOCS, whitespace (spaces, tabs, and line endings) is only for the visual clarity of the script, and capitalization is ignored for everything outside of quotes.

Words in quotes, eg. "NAME" are case-sensitive names of scripted content items such as techs, buildings, or specials. The names of the items are defined in their description by their line:

name = "NAME"

These items may be referred to in other items' descriptions by "NAME". This might typically be done when unlocking a building with a tech, or adding or checking for the presence of a special to or on an object.

Comments may be added to files using c/c++-style comment blocks. Anything in such blocks will be ignored when parsing the content files. Anything after "/*" will be ignored until the next occurrence of "*/" (even if it occurs several lines later), and anything on a line after "//" will be ignored.

In the FOCS descriptions below, the fixed portion of the FOCS specifications are in lower case or MixedCase; things written in ALLCAPS are placeholders for scripted subcontent. That type of any such piece of scripted subcontent below is specified either as a Condition, an Effect, an EffectsGroup, a string, an int (integer), or a double (a "real" number such as 2.4). In many cases, any such string, int or double can be provided either as a simple constant or as a more complicated scripted ValueRef. In any situations where a plain constant is required (but not a ValueRef), we endeavor to specify those values as string_constant, int_constant and double_constant.

Specification Components

There are a number of specification components that are used by multiple different content types, and some that are particular to a specific kind of content. The more common components are described first below.

ValueRef

A ValueRef is a type of FOCS construction which gets evaluated to provide a value, and which may reference various objects and which may have conditional aspects; their structure is described in more detail below. The most common types are string (text) ValueRefs (which generally evaluate to the name of something, such as a species name "SP_HUMAN"), integer ValueRefs (which evaluate to an integer, such as 42), and double ValueRefs (which evaluate to a "double", a programming term for a "real" number, i.e., it may have a decimal point, such as 3.5). Some ValueRefs may evaluate to a kind of FO-specific value such as a PlanetEnvironment or PlanetSize; it may be helpful to think of these as a string or number for which a limited group of values are acceptable.

Condition

A FOCS Condition acts as a kind of filter on objects in the FO universe. Conditions start with a set of objects, and return subsets of this set according to whether the objects meet the criteria of the condition. Just what that starting set of objects is depends on where the Condition is used, and is discussed more below. There are many different types of FOCS Conditions, and their structures are also explained further below.

Name Specification

name = "NAME"

Param Type:

NAME string_constant

When displayed to a user, the name will normally be used as a key/label for which a value will be looked up in a stringtable (to enable translation); the raw FOCS name strings themselves are by convention written in ALL_CAPS_WITH_UNDERSCORES. They should generally be unique to that particular piece of content-- even if both pieces of content might be suitably translated to the same name in English, that might not be the case for other languages. As examples, the name of the first refinement of the first tier of short range weapon parts (which is currently called "Mass Driver 1" in English) is specified as

name = "SR_WEAPON_1_1"

Description Specification

description = "DESCRIPTION"

Param Type:

DESCRIPTION string_constant

As with the name, the description is normally used as a key/label to be looked up in a stringtable, an example (specifically, for Mass Driver 1), would be

description = "SR_WEAPON_1_1_DESC"

BuildCost Specification

buildcost = BUILDCOST

Param Type:

BUILDCOST double (ValueRef)

BuildTime Specification

buildtime = BUILDTIME

Param Type:

BUILDTIME integer (ValueRef)

Location Specification

location = LOCATION

Param Type:

LOCATION Condition

In general, the Location specification constrains where/when the respective content can be built, or in the case of a Focus, be used. More detail is provided below for the various particular content types that use a Location specification. For things that can be built, if the item is under construction and the Location condition ceases to evaluate to True, then progress on the construction halts until such time as the Location condition again becomes True.

EnqueueLocation Specification

EnqueueLocation = ENQUEUELOCATION

Param Type:

ENQUEUELOCATION Condition

The EnqueueLocation condition sets the constraining condition under which the respective content (or a ship design using the content) may be placed on the Build Queue. If not explicitly specified, the EnqueueLocation condition will default to be the same as the Location condition. The EnqueueLocation is only evaluated at the time of placing the item on the queue; it need not remain true (and so, for example, may prohibit that the subject content is already enqueued at that location).

Describes the mechanism by which game content such as Techs, Buildings or Specials interacts with and alters the game state.

Consists primarily of:

One or more Effects

A "SCOPE" condition which indicates the objects in the scope of the Effect(s). The scope objects are those that are acted on by the effects in the effects group, i.e., what the targets of the effects are.

An "ACTIVATION" condition (assessed specifically against the Source) which indicates whether or not the Effect(s) will be executed on the objects in scope during the current turn. The default if the activation clause is left out, is to be on/active.

For scope conditions, the entire game universe (or rather, all objects in it) are the initial set. For activation conditions, the initial set is the source object of the effects group. This allows an EffectsGroup to be activated or suppressed based on the source object only (the object to which the EffectsGroup is attached). If the source object meets the activation condition, the EffectsGroup will be active in the current turn.

The translated stringtable entry in "DESCRIPTION" is amended to the source objects description (at the time of this writing, only for specials and species).

An EffectsGroup's stacking group determines when it should affect a specific target; if that target has already been affected by another EffectsGroup with the same stacking group, all EffectsGroups after the first have no effect on the target that turn. For instance, if an EffectsGroup is in a stacking group "WONDER_FARM_BONUS", and executes on a target object, no other EffectsGroup in the "WONDER_FARM_BONUS" stacking group will affect it on that turn.

The presence of "ACCOUNTINGLABEL" being specified indicates this effect should be accounted for with the supplied stringtable entry. This is typically used in providing feedback to the player, accounting for this EffectsGroup among the totals of effected meters.

"PRIORITY" is the order of the EffectsGroup processing. Processing starts from 0, with all EffectsGroups of the same priority executing before any of a later priority. This value must be an int and is specifically NOT a ValueRef ('1 + 1' is not allowed). Information on reference priority values, and the relative priorities of the set of population effects, can be found at our EffectsGroup Priority Standard Values page.

Each tech may optionally have one or more EffectsGroups associated with it.

Tech EffectsGroups are use as their source object the capitol planet of the empire that researches the tech.

All of a tech's prerequisites must be known before a Tech can be researched.

The noteTemplate:CN about Special and BuildingType name and description text also applies to Tech names, descriptions, and category names.

GRAPHICFILENAME should be relative to the art directory. So it should appear in the form "foo/bar.png" instead of "default/data/art/foo/bar.png".

Techs used in the game are stored within techs. These files include examples of theory techs with no effects or unlocked items, as well as applications that unlock buildings or which have effects of their own.

The Source for all EffectsGroups in a Tech is the Empire Source (generally the Capital), as discussed in the Source section.

Ship Part Class, Stats and PartMeters

Each class of ship parts defines a primary stat and may also define a secondary stat. Some have associated ship part meters (One meter value per ship object and ship part meter type). Possible ship part meter types are: Capacity, MaxCapacity, SecondaryStat, and MaxSecondaryStat.

Most parts classes (Armour, Bombard, Detection, Fuel, General, Shield, Speed, Stealth) only have a primary stat of capacity an no associated meter.

Troops and Colony part types have a primary capacity stat with associated Capacity meter.

FighterHangar has a primary stat of capacity and a secondary of damage (number of boats, damage of each boat's attack) and the associated MaxCapacity and MaxSecondaryStat meters.

Direct fire weapons (which only contains ShortRange currently) have a primary stat of damage and a secondary of shots.
shots determines how many times the weapon will fire each combat round.

LaunchBay parts have a capacity stat with associated (Max)Capacity meters which specifies how many space boats may launch per combat turn.

The meter value for a ship can be accessed using the ShipPartMeter part = "PART_NAME" meter = METER_TYPE object = SHIP_ID double complex variable. See above for which meters exist for which part class. Also note you can use Value(ShipPartMeter) to get the immediate/non-initial value. Defaults to 0.0

In the source code, the ship meters and ship part meters are defined in the Ship::Ship constructor in universe/Ship.cpp

PARTTYPE corresponds to the same ordered entry for each slot in HULLTYPE.

There must be the same number of PARTTYPEs as there are slots, but the PARTTYPE may be left empty ( "" ).

PARTTYPE must be compatible with the ShipSlotType for that slot.

ICONFILENAME and MODELNAME should be relative to the art directory.

Types and Expressions (ValueRefs)

In the Conditions and Effects below, there are parameters that specify details about how the condition or effect functions. These parameters can be specified as a constant number (eg. 5) or value (Blue), or can be variables that depend on the gamestate. Variables may refer to the Source, Target, RootCandidate or LocalCandidate objects (see below), a few independent values such as the number of the current game turn, or may refer to statistics about the gamestate that are calculated from multiple objects.

Source, Target, RootCandidate, LocalCandidate

ValueRefs, Conditions and Effects are evaluated in light of an automatically generated Scripting Context, which specifies one or more of a Source, Target, RootCandidate, and LocalCandidate. The way these get automatically generated depends on what content type is being evaluated.

For an Effect, the Source object is the object to which the Effect is attached. For example, a building might have an effect that increases a planet's industry meter. When defining that building's effects, the building itself would be the Source object. Regarding using "Source" as a Condition, as is common when specifying a scope, see the Conditions Section below.

The Target object of an Effect is the object that the Effect is modifying. In an effect that modifies a planet's industry meter, the planet would be the Target object.

The objects being tested by Conditions are candidates, and for reference within the scripts these are broadly divided into two types relating to the potentially multi-tiered nature of Conditions. Consider the following EffectsGroup scope condition:

Here there are two sets of objects being matched:
1) The objects actually being matched for the scope. These are objects within distance 5 of an object matched by the subcondition.
2) The objects matched by the subcondition, which are used to evaluate the outer condition. These are planets that are owned by the same empire that owns the object matched in the outer condition, and that have less than half their own target construction.

RootCandidate refers to the object being matched in the outer-most condition - WithinDistance in this case. This gives a way to refer to the object actually being matched by a big multi-part condition from one of the inner condition definitions, where the object being matched by a subcondition is likely not the same object being matched by the outer condition.

LocalCandidate refers to the object being matched in whatever condition it is directly in - the Construction meter condition in this case. This gives a way to refer to the object being matched by the current condition, regardless of what other conditions are matching outside or inside the current condition.

The RootCandidate and LocalCandidate may be used with the same types of variable references as for Source and Target.

For the EffectGroups in Techs, the Location specification, BuildTime value and BuildCost value for content such as a BuildingType, ShipHull or ShipPart, the context Source is the EmpireSource for the empire currently under consideration; this is its Capital planet if it has one, otherwise some other object owned by the empire. The Target in this context is the potential production location (planet) for which the Location, BuildTime or BuildCost is being evaluated.

For the Location specification for Specials, Source and Target are not set, but the LocalCandidate and RootCandidate references may be used.

For EmpireStatistic ValueRefs, the scripting context only has a Source, which is the EmpireSource mentioned above.

Free/Independent Variables

There are some variables that may be used without referring directly to the Source, Target or candidate objects. The current free variables that may be referenced are those specifying the galaxy setup conditions, and one which provides the current game turn. These currently all provide an integer result. For galaxy setup variables, their underlying type is generally a specialized enumeration which for this purpose gets mapped to an integer corresponding to the order they get listed in the GalaxySetup screen. For example, most galaxy setup variables work with range [None, Low, Medium, High], which gets mapped to [0, 1, 2, 3]. (Many of those variables drop the None value, and so have a range of 1-3.) Current Max AI Aggressions range from 0 to 5. The current list of free variables is:

Complex Variables

These variables are for values which need more than one parameter. These need at least one extra parameter to distinguish the right value and can not directly be accessed from an object. Instead you typically pass also the object ID (e.g. Source.ID, Target.DesignID) as parameter.

PartsInShipDesign name = "PART_NAME" design = DESIGN_ID

Returns the count of ship parts with the part name PART_NAME which are part of the ship design with the id DESIGN_ID. Will return zero if no such design exists or no such parts exist in the design.

SpecialAddedOnTurn name = "SPECIAL_NAME" object = ID

Returns the turn in the Special with the name SPECIAL_NAME was attached to the object ID. Will return zero if no such object exists or no such special was attached to the object (Note: this should be changed to a maximum turn number so SpecialAddedOnTurn <= CurrentTurn will be false if no special was attached to the object).

SpecialCapacity name = "SPECIAL_NAME" object = ID

Returns the capacity of the Special with the name SPECIAL_NAME attached to the object ID. Will return zero if no such object exists or no such special was attached to the object.

Returns the part meter value of a ship (as double). The meter value of the meter type METER_TYPE for the part with name PART_NAME of the ship with the id SHIP_ID.

Note you can use Value(ShipPartMeter) in effects to get the immediate/non-initial value. Will return 0.0 if the ship does not exist, the ship design does not have such a part, or the part class does not have this kind of meter associated.

Object Attributes

Object attributes are variables that are properties of the Source, Target, LocalCandidate, or RootCandidate objects. In combination these are also called "complex variables".

Some of the attributes have changing values which are tracked and manipulated as a meter. Usually these attributes return the initial value of the meter (before effects are executed), but one can access the current value changed by other effects using a Value() expression, e.g. Value(Source.TargetResearch) will return the current value of the Source object's TargetResearch meter.

List

Here is a (currently incomplete) list of the attributes available (but not necessarily currently used in-game), and their types (more on types later):

Age int the number of turns since the object was created
CreationTurn int the turn the object was created
ID int +++
Name string
LastTurnBattleHere int the last turn a battle was in the system or the system which contains this object
NearestSystemID int
NumSpecials int the count of specials an object has
ObjectType UniverseObjectType +! type of an object: Building, Field, Fleet, Planet, PopulationCenter, ProductionCenter, Ship, System
Owner int ++ the ID of the empire which owns this object
OwnerName string the name of the object's owning empire
OwnerLeastExpensiveEnqueuedTech returns the object's owner's empire's least expensive enqueued technology
PropagatedSupplyDistance double the object's system's propagated ??supply distance??
PropagatedSupplyRange double the object's system's propagated ??supply range??
Stealth double m the stealth value meter of an object e.g. a ship or a planet
SupplyingEmpire int ID of the empire which supplies the system which contains the object
System system ref the system of the object's containing system
SystemID int
X double X-Position of an object on the map (e.g. a field, fleet, system..)
Y double Y-Position of an object on the map (e.g. a field, fleet, system..)

Size double m Size: the size value meter of a field
Speed double m the starlane speed meter of a field (or ship) measured in AU distance

Construction double m construction value meter of a planet.
TargetConstruction double tm construction value target meter of a planet
DistanceFromOriginalType double distance of the current environment of a planet to the original environment type in steps (0,1,2,3, or 4)
Focus string the name of a planet's focus
HabitableSize double the habitable size of a planet - this depends on type of a planet and galaxy rule settings
Happiness double m happiness value meter of a population center (currently only planets)
TargetHappiness double tm happiness value target meter of a population center (currently only planets)
Industry double m industry value meter of a planet (not yet used for ships)
TargetIndustry double tm industry value target meter of a planet (not yet used for ships)
LastTurnAttackedByShip int turn number
LastTurnConquered
Orbit int the orbit ID of a planet where it is orbiting the star - i think this is only used for displaying the planets
PlanetSize PlanetSize + size of a planet compare with SizeAsDouble and HabitableSize
ClockwiseNextPlanetType PlanetType +
CounterClockwiseNextPlanetType PlanetType +
NextBetterPlanetType PlanetType + planet type with one step better environment for a planet's species
NextCloserToOriginalPlanetType PlanetType +
OriginalType PlanetType +
PlanetType PlanetType + the type of planet
PlanetEnvironment PlanetEnvironment + the environmental property for the planet's species from good to hostile
Population double m population value meter of a population center (currently only planets)
TargetPopulation double tm population value target meter of a population center (currently only planets)
Research double m research value meter of a planet (not yet used for ships)
TargetResearch double tm research value target meter of a planet (not yet used for ships)
RebelTroops double m RebelTroops: not used yet
SizeAsDouble double The size of a planet as a double value. Compare with PlanetSize, HabitableSize, and PlanetType
Stockpile double m imperial stockpile value meter of a planet
MaxStockpile double mm imperial stockpile value max meter of a planet
Supply double m supply value meter of a planet
MaxSupply double mm supply value max meter of a planet
Trade double m Trade: not used currently
TargetTrade double tm TargetTrade: not used currently
Troops double m troop count target meter of a planet (?? maybe the count of troops on a ship ??)
MaxTroops double mm troop count max meter of a planet
Defense double m defense value meter of a planet
MaxDefense double mm defense value max meter of a planet
TurnsSinceFocusChange int number of turns since focus was last changed

Detection double m the detection range meter of a ship or a planet
PreferredFocus string the preferred focus type of a ship's or a planet's species
Shield double m the shield value meter of a ship or a planet
MaxShield double mm the max shield value meter of a ship or a planet
Species string species' textual id of a ship's (or fighter's) crew or a planet's population
SpeciesID int species' numerical id of a ship's crew or a planet's population

ETA int turn number
FinalDestinationID int the id of a fleet's final destination system
NextSystemID int the id of the system a fleet is heading to/passing next
NumShips int
PreviousSystemID int the id of the system a fleet was coming from

LaunchedFrom int the id of the carrier ship a fighter was launched from (only in combat)
Species string species' textual id of a fighter's (or ship's) crew (or a planet's population)

BuildingType string the name of a building's type as specified in FOCS
Planet planet ref the planet a building is located on. E.g. Source.Planet.ID

PlanetID int the id of the planet a building or a ship is located
ProducedByEmpireID int the id of the empire which produced a building or ship
FleetID int the id of a fleet or the fleet a ship belongs to

+ The valid values for these types are listed after the corresponding conditions below. These values may change however, so for the most up-to-date list, it may be necessary to consult the FreeOrion source code.
++ Owner will return -1 if there are no owners (such as for a roaming space monster or unexplored system)
+++ This is the unique integer ID used to identify an object internally within FreeOrion.
++++ This is the unique integer ID used to identify a ship design.
m This is tracked using a meter. There might be a connected target meter or max meter
mm This is tracked using a max meter.
tm This is tracked using a target meter.
! While the code distinguishes between ProdCenter and PopCenters there is currently no overlap it is always a Planet ~~The types returned by ObjectType have some overlap. For instance, a Planet is also a PopCenter and a ProdCenter. In this case, Planet is returned before PopCenter or ProdCenter, since if you see a Planet, you know it is a ProdCenter, but seeing a ProdCenter, you have no idea if it is a Planet or something else that produces goods or resources, for instance a mining outpost. This principle guides the order in which type is determined when ObjectType is used.~~

The reference for the attributes is the file universe/ValueRef.cpp

Value

As a special case, there is a utility variable available that is used like a free variable, but actually refers to what is being modified by an effect:

Value double, int, string, PlanetSize, PlanetType, StarType

The value of "Value" is the initial value (before the current effect acts) of whatever is being set. For example, in a SetStealth effect, "Value" would return the same as "Target.Stealth". For SetPlanetType, "Value" would return the same as "Target.PlanetType".

The type returned by "Value" depend on the type of effect in which it is used. For meter-setting effects Value will be a double. For SetPlanetSize, it will be a PlanetSize, and similarly for PlanetType, PlanetEnvironment, StarType. For setting a planet's species, Value will be a string.

Do not confuse this with the Value() expression, which is used to get the current value of a meter using a complex variable.

Statistics

Statistics are values calculated from a sampling of objects in the game universe, which may or may not include the Source and Target objects.

List

The available statistical calculations that can be performed on the property values of objects matching the sampling condition are:

If - Returns 1 if at least one object matches the selection condition, or 0 otherwise
Count - Returns the number of objects that match the selection condition
UniqueCount - Returns the number of unique values of the property are present among objects that match the selection condition
Sum - Returns the sum of property values of objects that match the selection condition
Mean - Returns the arithmetic mean of property values
RMS - Returns the square root of the arithmetic mean of the squares of the property values
Mode - Returns the most common property value
Max - Returns the largest property value
Min - Returns the smallest property value
Spread - Returns the difference between the largest and smallest property values
STDEV - Returns the standard deviation of the property values
Product - Returns the product of multiplying all the property values together

Mode may be used for any type of parameter, including enumerated types like PlanetSize and double or int or string. The other statistic types may be used only for parameters that are int or double. If and Count may be used without specifying a property value.

Use

Constants

In item descriptions, parameter values such as LOW, HIGH, or NUMBER may be simple numbers, like 5 or 10, in which case all objects with the appropriate meter are treated the same by Turn.

Variables

Parameter values may also be defined in terms of attributes (or "properties") of the Source, RootCandidate, LocalCandidate or Target object. In these cases, different objects may be differently matched or not, if the property used differs between them.

Object attributes can be referenced on the source or target object, but not alone. So "Source.ID" and "Target.PlanetSize" are legal variables, but "PlanetEnvironment" in isolation is not.

Parameter values may also be defined in terms of the free variables mentioned above that are not associated with a particular object. In this case, the variable name is used without any object reference; for example, "CurrentTurn" returns the current game turn.

Parameter values for meter-altering effects may also refer to "Value" which is equivalent to referring to the meter of the target object that is being altered, depending which meter-setting effect is being used.

In addition, an object's containing object, if one exists, may be used in a variable. For instance, if the source is a planet, "Source.System.StarType" represents the star type of the source's system. Planet may also be used in a similar fashion, as in "Target.Planet.PlanetEnvironment".

Nonsensical combinations of Target, Source, Planet, System, and the above attributes are allowed, but will always return 0 for numeric values, and a special value representing an invalid value for enumerated type values. The special invalid value is guaranteed not to match the value of any actual object.

For example, if the source object is a System, Source.System.StarType will always return an invalid Star Type.

Similarly, Target.System.Industry makes no sense (since industry meters meters exist for Planets but not Systems), and so will return the double value 0.0.

Statistics

Parameter values may also be defined in terms of statistics calculated from the gamestate. A statistic returns a value based on the specified property, calculation and a condition to select objects in the game Universe.

In any place where a constant or variable could be specified, a statistic may be used instead. The format for a statistic calculation is:

Statistic STATISTIC_TYPE value = VALUE condition = SAMPLING_CONDITION

For example, to calculate the sum of all planets' populations,

Statistic Sum value = LocalCandidate.Population condition = Planet

The result would return a double value, which will be used just as if a constant like 42.4 had been specified, or a variable like Target.Population had been specified.

Types

The "double" type listed above, is a double-precision floating point number, which is more or less any real number in the range [-10^300, 10^300]. The "int" type is an integer number, which is basically any whole number in the range [-2*10^9, 2*10^9]. The other types are enumerated types, with specific values. Each such value has a string associated with it, for instance the first valid StarType is Blue.

In the Conditions and Effects below, certain parameters have types. It is illegal to provide a parameter of the wrong type, and it will result in a thrown exception (a purposeful crash of FreeOrion). There is one major exceptions to this. It is legal to provide a int value for any parameter of any type. This is mainly to support easy expression syntax, which is the next thing that needs to be addressed.

Instead of providing a singe variable or constant value (such as 3.14, 5, or STAR_BLUE), you can instead provide an arithmetic expression. Legal expressions may contain parentheses, +, -, *, / and ^ (for exponentiation). The - operator can be binary as in "3 - 4", or unary as in "-Source.MaxHealth". Whitespace (spaces, tabs, and newlines) is ignored. Expressions may be arbitrarily complex. The type of the entire expression must match the type of the parameter for which it is intended. For instance, it is illegal to supply "1 + 3.14" as a value for an int-type parameter, since 3.14 is not an int. As mentioned before, though, it is legal to supply "STAR_BLUE + 1" as a value for a StarType parameter, since integers are always ok.

Note that since arbitrarily complex expressions are allowed in Effects, and multiple Effects may affect a single target in a single turn, the order in which the Effects are applied to the target may matter. For instance, if Effect A sets the current industry meter to "Target.Industry + 20", and Effect B sets the current industry meter to "Target.Industry * 3", the answer could be X * 3 + 20 or (X + 20) * 3, depending on the order of execution. To minimize this, and in keeping with the guidelines for Effects in general, such Effects should have small magnitude, which will make the problem largely disappear. For instance, if "Target.Industry + 3" and "Target.Industry * 1.05" are used instead, the difference between X * 1.05 + 3 and (X + 3) * 1.05 is a negligible 0.15.

Note that some of the parameters in the Conditions and Effects below ask for a certain type, sometimes a type-expression. Those parameters that do not explicitly allow type-expressions cannot handle them.

Value

The Value parameter for a statistic can be practically any kind of ValueRef, including complex expressions. The one exception that comes to mind is that attempting to use a statistic as the Value for another statistic has had parsing problems which may not yet be fully resolved.

Conditions

The syntax {a|b|c} below indicates a choice of values, exactly one of which must be selected. The brackets and vertical lines are not legal to use themselves.

{a|[a b c ...]} indicates that a single item may be specified ( a ), or multiple items in a list ( [a b c ...] ).

"low = ", "high = ", etc., indicates an *optional* parameter name. All parameters must appear in the order indicated, so the names are not necessary to indicate which value is meant for which parameter. The name may be included, however (except for with the And, Not and Or conditions, which do not have or allow such parameter names).

General

All

Matches all objects.

Source

Matches the Source object.

Target

Matches the target object of an effect. This can be used within effect definitions, but not within scope or activation condition definitions, as when those conditions are evaluated, the target object hasn't yet been determined.

Turn low = LOW high = HIGH

Matches objects if the current game turn is greater than or equal to LOW and less than HIGH.

NumberOf number = NUMBER condition = CONDITION

Matches at most NUMBER objects that match CONDITION. If fewer than NUMBER objects match CONDITION, all such objects are matched. If more than NUMBER objects match CONDITION, NUMBER such objects are randomly selected and matched.

These variants of NumberOf take a SORTKEY argument which is used to sort the objects matching the CONDITION before the elements get selected. The SORTKEY is a double valueref (e.g. such as LocalCandidate.Happiness).
MinimumNumberOf will select and match (up to) NUMBER objects which have the smallest SORTKEY value of all matching objects.
MaximumNumberOf will select and match (up to) NUMBER objects which have the highest SORTKEY value of all matching objects.
ModeNumberOf will select and match (up to) NUMBER objects which have the most frequent values of all matching objects' SORTKEY values (e.g. you could a match a number of planets with the most common defense meter value).

Number low = LOW high = HIGH condition = CONDITION

Matches all objects if the number of objects that match CONDITION is greater than or equal to LOW and less than HIGH. Objects matched may or may not themselves match CONDITION.

Random probability = PROB

Matches objects with a probability of PROB. That is, objects have a probability of PROB of being matched.

Matches objects where the empire with the indicated id EMPIRE (or any empires if none is specified) have within the indicated range (LOW to HIGH inclusive) of the indicated type of production item with the indicated name or design ID (NAME or DESIGN ID) and TYPE (Building or Ship). The count used to assess LOW and HIGH takes into account the element blocksize.

Planet / Star

Planet type = {TYPE|[TYPE0 TYPE1 TYPE2 ...]}

Matches objects that are or are contained by planets that have the indicated type.

Matches objects that are or are contained by planets that are the indicated size.

Sizes are:

Tiny
Small
Medium
Large
Huge
Asteroids
GasGiant

Planet environment = {ENV|[ENV0 ENV1 ENV2 ...]}

Matches objects that are or are contained by planets that have the indicated environment.

Environments are:

Uninhabitable
Hostile
Poor
Adequate
Good

HomeWorld
name = {SPECIES|[SPECIES0 SPECIES1 ...]} [optional -- may be left out]

Matches planets that are homeworlds to playable species. If no species are specified, the homeworld of any species will be matched.

SPECIES the name of a species in the game, as defined in a species definition file

Capital

Matches planets that are capitols of an (any) empire. Use in combination with OwnedBy for a specific empire's homeworld.

Star type = {TYPE|[TYPE0 TYPE1 TYPE2 ...]}

Matches objects that are or are contained by systems that have the indicated star type.

Types are:

Blue
White
Yellow
Orange
Red
Neutron
BlackHole

Infrastructure / Focus

Focus focus = {FOCUS|[FOCUS0 FOCUS1 FOCUS2 ...]}

Matches planets that have the indicated focus or any of the indicated foci.

FOCUS or FOCUS# are strings. Each species may have a different set of foci available, but typical focus options include "FOCUS_GROWTH", "FOCUS_INDUSTRY", "FOCUS_LOGISTICS", "FOCUS_PROTECTION", "FOCUS_RESEARCH", and "FOCUS_STOCKPILE"

To check if a given focus (FOCUS_RESEARCH in the below example) is simply available at a planet (even if not actually selected), the following check can be used:

Matches objects with the appropriate meter values that are greater than or equal to LOW and less than or equal to HIGH. That is, LOW specifies the lowest allowed value of the meter, and HIGH specifies the highest allowed value. Either of the LOW and HIGH parameters may be omitted, in which case there is no limit on the meter value in that direction. For example, if only LOW is specified, there is no upper limit on the allowed meter value.

The HasSpecialCapacity uses the capacity meter of the special given as string name. The HasSpecialSinceTurn queries the turn a special was first set on an object.

Object Owner / Producer

Matches objects owned by (OwnedBy) an empire with the indicated affiliation to the indicated id EMPIRE. EMPIRE may be omitted with using AnyEmpire, which will match objects owned by any empire, regardless of what EMPIRE is specified (or not). Typically EMPIRE is specified as a function of an object, such as Source.Owner, however a constant integer such as 2 may also be specified.

Matches objects with exactly one owner, whose owner's stockpile of the appropriate resource is greater than or equal to LOW and less than or equal to HIGH.

OwnerHasTech name = "NAME"

Matches objects with exactly one owner, whose owner has the tech NAME.

Note: This is useful for refinements of technologies, where a refinement tech is indicated by NAME in an effects group of the item being refined.

VisibleToEmpire empire = {EMPIRE|[EMPIRE0 EMPIRE1 EMPIRE2 ...]}

Matches objects that are visible to the indicated empire(s).

ProducedByEmpire empire = EMPIRE

Matches buildings or ships produced by the empire with id indicated by EMPIRE. Typically EMPIRE is specified as a function of an object, such as Source.Owner, however a constant integer such as 2 may also be specified. Note that ownership and who produced an object aren't necessary the same, particularly for buildings, which may be captured with planets from other empires.

Ship Design

Design name = "NAME"

Matches ships that have a design generated from the predefined designs in ship_designs/ or monster_designs/.

Design design = DESIGNID

Matches ships that have the specified ship design ID. Most likely this would be Source.DesignID

DesignHasHull name = "NAME"

Matches ships that have the indicated hull in their design.

DesignHasPart low = LOW high = HIGH name = "NAME"

Matches ships that have >= LOW and < HIGH of the part NAME in their design.

DesignHasPartClass low = LOW high = HIGH class = CLASS

Matches ships that have >= LOW and < HIGH of parts of the indicated PartClass in their design.

Armed

Matches ships that have weapons.

Monster

Matches space monsters.

Galaxy Map Position

WithinDistance distance = DISTANCE condition = CONDITION

Matches objects that are within the indicated Euclidean direct-line DISTANCE of any objects that matches CONDITION. The matched objects may or may not themselves match CONDITION.

WithinStarlaneJumps jumps = JUMPS condition = CONDITION

Matches objects that are within the indicated number of starlane jumps (crossings from one star to the next) of any objects that matches CONDITION. The matched objects may or may not themselves match CONDITION.

Stationary

Matches objects that are not moving. The only objects that move are fleets and ships. Objects are not stationary if they are going to move, so fleets ordered to move are not stationary, but fleets that arrive in a system are stationary on the turn after they arrive.

ResupplyableBy empire = EMPIRE

Matched objects should be in systems where the empire with id EMPIRE can provide fleet supply.

ResourceSupplyConnected empire = EMPIRE condition = CONDITION

Matched objects should be in systems connected by resource sharing lines for the empire with id EMPIRE to at least one object that matches the sub-condition CONDITION. Objects outside systems shouldn't be matched, regardless of whether they're on a starlane that is connected to an object that matched the sub-condition.

Conditional

Conditional conditions are variants of some kind of "if". The only conditional condition we have currently is OrderedAlternativesOf, in some cases one can use the If statistic in ValueRef statements to get conditional results.

The OrderedAlternativesOf provides the ability to conditionally match the objects of the first condition inside of it which matches at least one local candidate.
An example from FT_HANGAR_1 (Note that COMBAT_TARGETS_VISIBLE_ENEMY has to be repeated inside each single tier condition)

Matches objects that match at least one, or more, of the indicated subconditions.

Not CONDITION

Matches objects that do not match CONDITION.

Notes

Implicit ContainedBy

Some Conditions that match an object's containing object will be returned, even though they at first seem to be nonsensical. For instance, if the target object is a Planet, StarType will match the type of the System in which the target is located. This means that StarType will match all objects in all Systems with the given star type, and the Systems themselves. Similarly, all objects on all Planets (and the Planets themselves) that match a PlanetType, PlanetSize, or PlanetEnvironment will be matched. This has an important implication; if you want all Systems with blue stars, you should use

And [
Star type = Blue
System
]

If you want all Ships in Systems with blue stars, you should use:

And [ Ship Star type = Blue ]

And & Or Efficiency

The And and Or Conditions are designed to work as efficiently as possible, by only searching the objects that have not already been matched. So it is always best to put the most restrictive Condition first in an And Condition's list of subconditions.

For instance, if "Star type = Blue" matches about 1000 objects,

And [ Source Star type = Blue ]

will be about 1000 times faster than

And [ Star type = Blue Source ]

This is because the former only has to look at the match from Source to see if it also is (or is inside of) a blue-starred System, whereas that latter has to look through the 1000 matches of objects that are or are in blue-starred systems, to see if any of them also matches Source.

If the target of the Effect does not have the requested meter, nothing is done.

Typically, meter-setting effects do so by adding or subtracting form the same meter value of the Target. For example,

SetTargetResearch Target.TargetResearch + 5

or

SetHealth Value - 10

The value "Value" always refers to the present value of the meter being set, allowing incremental changes to meter values without the cumbersome use of references to the Target such as "Target.FoodConsumption" (for the Target's food consumption meter) which would instead be just "Value" when using the SetFoodConsumption effect.

When a "max" (eg. MaxStructure) or "target" (eg. TargetPopulation) meter value, or another meter for which there is no associated "max" or "target" meter (eg. Stealth), the change is non-persistent. This means that every turn, the meter is reset to 0, and all effects must re-act on the meter for it to retain a consistent value. If on a subsequent turn, the effect does not at on that target, the meter value will return to its previous value (or whatever value all other effects acting on it produce).

When a meter (eg. Structure) has an associated "max" or "target" meter (eg. MaxStructure), the meter value IS persistent. Repeatedly applying the same effect every turn will accumulate. If an effect reduced an object's Health meter by -2 every turn, the 2nd turn would have a net -4 reduction, the 3rd turn would have a net -6 reduction, etc. If an effect alters such a meter once, then does not act again, the meter stays reduced, until other effects increase or decrease it, or it increases or decreases itself over time towards its associated target or max value.

SetOwnerCapitol

Sets the target object to be the capitol of its owner's empire. If the target is not a planet, or is not owned by a single empire, nothing is done.

SetPlanetType

SetPlanetType type = TYPE

Param Type:

TYPE PlanetType

Sets the planet type of the target to TYPE.

Has no effect on non-Planet targets.

Changing type from Asteroids or GasGiant to something else will also change its size to Tiny or Huge, respectively.

Changing type to Asteroids or GasGiant will also cause the size to change to Asteroids or GasGiant, respectively.

SetPlanetSize

SetPlanetSize size = SIZE

Param Type:

SIZE PlanetSize

Sets the planet size of the target to SIZE.

Has no effect on non-Planet targets.

Changing the size of a Asteroids or GasGiant planet will also change its type to Barren.

Changing size to Asteroids or GasGiant will also cause the type to change to Asteroids or GasGiant, respectively.

SetOwner

SetOwner empire = EMPIRE

Param Type:

EMPIRE int

Sets empire EMPIRE_ID as the owner of the target.

Has no effect if EMPIRE_ID was already the owner of the target object.

CreatePlanet

CreatePlanet type = TYPE size = SIZE

Param Types:

TYPE PlanetType
SIZE PlanetSize

Creates a new planet at the location of the target object. If the target object is not located in a system, nothing is done. If there are no free orbit slots at the target object's system, nothing is done.

CreateBuilding

CreateBuilding name = NAME

Param Types:

NAME string

Creates a new building at the location indicated by the target object. If the target object is not a planet, nothing is done.

CreateShip

CreateShip
designname = "NAME"
empire = EMPIREID
species = "SPECIES"

ParamTypes

NAME string_constant
EMPIREID int_constant
SPECIES string_constant

Creates a new shipat the location of the target object. The design of the new ship is indicated by the NAME parameter, which looks up the design in premade_ship_designs.txt in the default folder. EMPIREID is the id of the empire who should own the newly created ship, which is probably the id of something related to the source or target objects. SPECIES is the name of the species which should crew the newly created ship, which can be something related to target or source objects, or an explicit species name.

Destroy

Destroy

Destroys the target object.

The Destroy effect will not destroy a System object, although any other objects in or outside a system can be destroyed.

Destroy effects are executed after all other effects.

Destroying a fleet will destroy its ships.

Destroying all the ships in a fleet will destroy the fleet.

Destroying a planet will destroy its buildings.

AddSpecial

AddSpecial name = "NAME"

Param Type:

NAME string_constant

Adds the Special with the name NAME to the target object.

Note that using a wrong NAME/a NAME for which no special is specified is possible but will lead to strange behaviours

You can retrieve the turn a Special was added using the SpecialAddedOnTurn complex variable

RemoveSpecial

RemoveSpecial name = "NAME"

Param Type:

NAME string_constant

Removes the Special with the name NAME to the target object.

Has no effect if no such Special was already attached to the target object.

SetSpecialCapacity

SetSpecialCapacity name = "NAME" capacity = NUMBER

Param Type:

NAME string_constant
NUMBER double (ValueRef)

Sets the capacity of Special with the name NAME to the given NUMBER.

Adds the Special if no such Special was already attached to the target object.

If such a Special was attached, this won't change the since turn value (queried by HasSpecialSinceTurn)

Object candidates can be filtered using the HasSpecialCapacity condition

The special's capacity value can be retrieved using the SpecialCapacity complex variable

SetStarType

SetStarType type = TYPE

Param Type:

TYPE StarType

Sets the star type of the target to TYPE.

Has no effect on non-System targets.

MoveTo

MoveTo location = CONDITION

Param Type:

LOCATION Condition

Moves the target object to the location of one of the objects matched by LOCATION

If no objects match the location condition, nothing is done.

If more than one object matches the location condition, one object is chosen by the condition

If the target object is a ship and the location object is a fleet or a ship (in a fleet) owned by the same empire, the ship is inserted into the fleet.

If the target object is a ship and the location is not a fleet into which the ship can be inserted, a new fleet is created for the ship a the new location.

If the target object is a ship and its location is the same system but not a different fleet, nothing is done and the ship is left in its original fleet.

If the target object is a fleet and its location is a fleet or ship outside a system, and a fleet is moved to or created at the target location, the fleet will be moving to the same system as the taget object fleet.

If the target object is a building and the location object is a planet or a building on a planet, the building is added to the planet.

If the target object is a building and the location is not a planet or on a planet, nothing is done.

If the target object is a planet and the location object is not a system or in a system, nothing is done.

If the target object is a planet and the location system has no empty orbit slots, nothing is done.

If the target object is a system, nothing is done.

Any target object moved to the location of a system will be inserted into that system.

SetEmpireTechProgress sets the amount of research points (RP) the indicated empire has accumulated towards researching the indicated tech (limited to between 0 and the total RP cost of the tech).

Victory

Victory reason = "REASON"

Param Type

REASON string_constant

Victory causes the owner of the target object to win the game. Losing human players (which is any player who has not won on the turn a player wins) are ejected from the game. The string REASON is d_constantisplayed in a popup to all players, with the name of the winning empire inserted as the %1% parameter to the string.

AddStarlanes and RemoveStarlanes

AddStarlanes adds starlanes between the target system and any system containing an object that matches CONDITION. RemoveStarlanes removes starlanes between the target system and any system containing an object that matches CONDITIONS. Adding a starlanes where one already exists, or removing a starlane wher none exists does nothing.

MoveTo

MoveTo destination = CONDITION

Param Type

CONDITION condition

MoveTo moves the target object to the location of the / one of the objects matched by the CONDITION parameter.

SetDestination

SetDestination destination = CONDITION

Param Type

CONDITION condition

SetDestination sets the travel route of the target fleet to be the shortest path for the target to move to an object that matches the CONDITION parameter. If multiple objects match CONDITION, one is chosen. If the target fleet can't move to the chosen object, nothing is done. The shortest path for the object may depend on the empire that owns it (if any).

SetAggression

SetAggressive
SetPassive

SetAggressive marks a fleet as aggressive, meaning it will block enemy supply, and engage any enemy fleets or planets in its system. SetPassive marks a fleet as passive, meaning it will not block supply or initiate combat. Remaining passive may be useful for staying hidden in a system (if stealthy) or to make non-aggressive monster types not attack player fleets.

SetSpecies

SetSpecies name = "NAME"

Param Type

NAME string_constant

SetSpecies sets the species of the target ship or planet to the indicated species NAME.

SetVisibility

The following details for this Effect correspond to the modifications currently proposed in PR 1764, please note some constraints/complications regarding priority and timing of evaluation as discussed in the PR.

AFFILIATION optionally specifies an empire affiliation. Defaults to TheEmpire if an empire ID is specified, or AnyEmpire if no empire ID is specified.
EMPIRE optionally specifies an Int ValueRef specifying an empire ID, which is used with the affiliation to determine which empire's visibility/ies to set. Defaults to an invalid empire ID if none is specified, which will work with affiliations that aren't relative to a particular empire.
VALUEREF A Visibility type ValueRef, can include expressions like max(Value, V) where Value refers to the current visibility
CONDITION optionally condition specifies the object(s) whose visibility is to be set. If no condition is specified, the effect target object's visibility is set.

Effect Evaluation & Application Ordering

Effects are evaluated and then applied while processing a FreeOrion turn. When this happens, all EffectsGroups' activation and scope conditions are evaluated before any effects are applied.

The order of effects' application is determined primarily by their specified Priority (beginning at 0).

For EffectsGroups sharing the same Priority number their secondary ordering is determined by their source/cause, as follows: effects from Species, then effects from Specials, then effects from Techs, then effects from Buildings, then effects from Ship Hulls, then effects from Ship Parts.
The order of execution of Effects within these groups is deterministic, though not controllable.

Multiple effects scripted into the same item will be evaluated in the order in which they appear.